You have multiple issues that are contributing to make you feel uncomfortable so it is hard to say which is the real problem. So let's address each separately.
As a woman, I can tell you that you are ahead of the game as you describe your co-workers as nice guys. So it is worth it to get more comfortable working with these guys before you face the not-nice guy variety at work.
Women walk a tightrope between being thought of a decorative but a little dim or bitchy. Actions which would make a man be treated as an equal can throw a woman to one side or the other of the tightrope. You need to be friendly but not too friendly, assertive but not too assertive, etc. It is not easy. It gets easier as you get more experience. In an all male team, they too may be feeling unsure about how to deal with you. Let that give you some confidence.
The main thing you have to do is first establish yourself as a knowledgeable professional. Start by contributing to technical discussions. Don't be surprised if people interrupt you or seem not to hear what you said. That is common and tha books I reference below will help you with that.
Women in general tend to contribute less when they feel they are not expert, but men are often socialized that is is OK to state your opinion even if you are not sure. So they appear more confident and they appear to have more expertise than you do because they speak up confidently.
You need to start speaking up. You also need to become aware of how you speak. You need to use the same type of language that they do. Women tend to use a question tone for their statements, men do not. That makes you appear less confident. So that is one thing to look at fixing.
There is a woman who specializes in studying language who has written several very good books. You need to read them to learn how to communicate so that men will better understand what you are saying and you will show more confidence and feel better about how you are being perceived.
All working women who use English should read these two books. Men should too. This is an important subject.
These books are likely to help you a lot in understanding how men communicate and how women do. Truly it is almost as if we speak different languages and as an immigrant, this is probably even more pronounced for you.
You say you enjoy comics, start chatting about that even if you don't feel you are an expert. If you read the latest comic in a series then just make a comment about the story line or how you didn't see such and such coming or how sad it was that this character died or whatever. It will make you fit in better even if you are not an expert. Most of the comic book talk should be relatively opinion based anyway. You liked or didn't like the new story line. This character impresses you more than that character, etc. Your opinion is just a valuable as theirs.
From the viewpoint of being an immigrant, you may also be having to deal with the different roles that women play in different cultures. In many countries the issues Deborah talks about in her books are even more pronounced because women are socialized even more to not speak up.
I don't know what culture you are from, but you need to find a woman from the country you are in to help mentor you on how people behave in your new country in the workplace.
You may even need to learn to project one persona at work and another in your private life if you mostly hang out with people from your home country and if you are married to someone else from your home country.
So you also need to make friends with those non-developer women in your office and get them to answer cultural questions for you. For instance, I know in some countries the workplace is far more hierarchical than it is in the US. So a person following the norms of his or her country might also appear unconfident to an American audience.
You need a guide to these matters and it actually helps if this person is not one of the team members you work with daily.
You might also go to some local user group meetings and see if you can connect with a women working at another company in your field. If you can connect to a local woman who has been here longer but comes from another culture (even if not your own), that is even better because they had to face the cultural adjustments and will know things that the people in the new country take from granted and would never think to explain. Having someone to share your questions with in a safe environment is crucial to learning to get comfortable operating in the culture you are living in. It may be your colleagues seem so much more confident to you because they too are communicating in a different style than you are used to from the men in similar positions in your home country.
How to feel welcome in an unfamiliar software developer environment. The gender isn't that much important here and doesn't need to be specified in the title. But other than that, your question is well explained and detailed. Now, to the point. I'm a male developer and I have huge struggles in socializing, since most people have nothing in common with me. If you want to fit in the group where you have things in common, show your interest in those things. You may hate sports (I hate football/soccer) (continue...)