The first thing you have to understand is that working from home is a burden on the company, it makes it harder for the team to work together and it is up to you as the person working there to relieve their anxieties. Working from home involves much more communication daily than you apparently give.
First thing is to get your schedule out into the open and firmed up. If no one knows what days that you are working from home, then they will wonder what you are doing. Working from home without telling them in advance becasue you are too tired to come in is especially bad. Remember that dirty trays on the the airplane make passengers wonder how well the airplane engine is maintained and you are exhibiting dirty pull-down trays right now.
Next you need need to work with the project manager and your team mates to improve communication. First, they need to know that you are contactable when you are home. In my office we have plenty of remote workers, but chosing to be out of touch daily is a good way to get fired. You need to talk to the PM about exactly what communication he expects from you daily. It does feel more micromanaged becasue it by necessity has to be more micromanaged. He can't see what you are doing, so he has to hear from you often.
In particular, make sure that people on your team know where your work is being stored on the network if it is in a different location that where they put theirs. Make sure everything is accessible to them if they can't get a hold of you. Make sure to track progress in daily emails. Make sure to include your PM on all email communcations so he can answer questions if you are not there.
Developers like to have long stretches of uninterrupted time and can get away with that at the office through the use of headphones. You have no way to signal that uninterrupted time and not responding to emails, IMs and phone calls fairly quickly is the kiss of death when you are working remotely. So these two things are at odds. You need to be more interruptible when you work from home. You need to make sure that you are not the delay in someone else's workflow.
If you are working on something particularly tricky, tell the PM that you need to have from 3-6 uninterrupted to work on x and let the other team members know. And let them know a couple hours ahead of time, so if they need you for something that day, they can contact you before you go out of touch. And then when you get back on line (and you should even if the uninterrupted work stretch is at the end of the day), make sure they see you and that you tell the PM what you accomplished while out of touch.
You also apparently have new colleagues. You need to make friends with them. You need to IM them when you are home and chat some. You need to make sure to hang out in the office with them when you are in. The more they like you, the less likely they are to try to sabotage you as the person who isn't there. You need to learn to fit into the changed work culture if you want to stay there. If these new colleagues are all unmarried guys then they are most likely not going to want to hear about your baby except to knoe how you are going to keep it from being an issue.
Next you need to look at this workplace and see if it is still right for you. It seems that they are not very understanding of the challenges of parenthood. Those challenges aren't going to go away and you aren't ever going to fit into a frat boy atmosphere. You don't say how the culture has changed, but if this is the direction it has gone, you need to think about this.
If your office does not often use remote workers, you will have to work harder to convince them that it is working. That may not seem fair, but life is never fair. Further, there may be resentment if you can work from home and they cannot. This is especially true of you are different from them in some way such as being the only woman.
Not only are you holding your future on your ability to convince them that remote working is working out, you are going to be the test case for whether they let anyone else do it if this is not a common practice. On the other hand, if you can convince your other colleagues that if it works out well for you, they may be in a better position to get the same privilege for them, then you might gain them as allies not opponents.
Next, you need to be hard-headed about your work ethic. It is easy to slack off at home and not realize it. We have had employees like this who are twice as productive when working in the office as at home. of course there were also others who are more productive at home and others who are about the same where ever they are. What you don't want to be is in the first category, either really in the first category or perceived to be that way. The best way to fight the persception that you are slacking by working from home is to fall nto teh second category and visibly be more productuve at home. Remember, this all about perception. It isn't enough to be more productive, you have to be seen as being more productive.
Perception is really important and the need to make sure your actions are perceived properly increases exponentially when you work at home. At the office if someone sees you on Facebook, they think, well she is taking a break. Same if they see you headed to the bathrooms or in the kitchen. When working from home, if they try to contact you and you are not there, the immediate perception is that you are not really working.
So it is up to you to make sure you are available during the actual work hours ( not two hours in the morning, a three hour nap, then six more hours of work) and that you let people know when your lunch break is etc. Even when you are putting in the hours, if they are not during the times when other people are working, you will be thought of as a slacker. Now some of this can be relaxed once you have the reputation for delivering when you are home, but the first 6 months at least, you need to be be absolutely available during normal work hours or you need to have told the PM where you will be and when you are making up the hours (I presume you will have some followup doctor visits etc to attend to).
Working from home is privilege not a right. You need to start treating it as such. That means that your work performance needs to be better when working from home than it was when working in the office. You need to make sure to attend meetings by phone, you need to communicate frequently by email, phone and IM and you especially need to immediately communicate any roadblocks or reasons why a task may be delayed. You can't just communicate a roadblock either, you need to followup at a minimum of daily on that roadblock. YOu need to make sure that no request for information from you lies unanswered for every long and only rarely for as much as an hour.
Communicating with your boss about child care arrangements is not prying into your personal life. Get over that too. This person has a valid right to know that information as it affects the work. Co-workers don't need to know and you can deflect those questions although it often is a bad idea to do so. Refusal to answer these questions makes it look as if you have something to hide. It gives people the perception that you are trying to care for the baby and work and that means they will think you will be doing more baby caring and less work. Many people have worked with others who abused a similar situation and so are far less confident than you are that it isn't affecting your output when they hear the baby crying in the background for instance. The burden is on you to tell them what they need to know to be confident you can do the work assigned.