It's great that you've come to this realization yourself, as most would not innately recognize problems with their communication until someone else pointed it out to them - so you're on the right track. Let's take each of your points individually, and see where improvements can be made.
Panicking during Presentation
Many people have this problem, and the best way to solve this is practice. Check with local colleges around your area to see what classes they have in relation to public speaking. Many people blow off what it takes to effectively present an idea, but I can tell you that it is as much of an art form as designing/developing the product/service that the idea is itself.
Pressing Your Idea & The Idea Not Getting The Attention You Want It To
Unless your a salesman, it seems based on points 2 and 3 that you're getting too emotionally attached to whatever it is that you're presenting. You shouldn't be pressing your idea on anyone and only hoping that they come back with a pat on the back to tell you that they think your idea is great.
On the flip-side, you shouldn't be discouraged if you've presented an idea and that idea has been shot down, or has been declined for whatever reason.
If you're going into a presentation of your idea/product/service and you're only interested in hearing good news, then what is the point of presenting the product in the first place? For secondary validation? No.
You're presenting your idea so that others can give feedback. Your idea isn't perfect. If it was, you'd have developed a perfect product by now - and a perfect product doesn't exist. If your presentation is lack-luster, or you find that there are many people in the presentation that doesn't care for the idea then you need to take the criticism they've given you - and rework your idea. That withstanding, no one likes everything - and you will find that your idea/product/service isn't liked by all. That's also OK, that's why we have market segments.
Summary
You're too emotionally invested in whatever it is you are presenting/discussing. Detach yourself from it. You'll have a million other presentations/discussions in your lifetime, and working yourself up over each one is cause for an early grave. Take the feedback (in whatever position that person is in) and go back to the drawing board with your idea/product/service and properly analyze if the other person's criticism has any merit.
Personal Experience
I'll throw in my own personal experience into the mix. When I'm presenting a new idea/product/service to prominent leaders at my workplace - I usually carve out around 65-80 hours to outline, prepare my speech, identify any common questions, and create the presentation. Presenting is A LOT of work, and throwing something together last minute and hoping that people latch on to whatever it is that you're presenting will more-often-than-not lead to you getting caught with your pants down.
Additionally, prior to deciding that I want to actually present the idea, I'll bounce the idea off of a few people. These people WILL NOT be my colleagues, anyone on my team, my department, or anyone related to the idea if it actually becomes a project. Instead, I'll bounce the idea off of my wife, family members, the administrative assistant down the hall, my mail man, etc. - and tell them in a way that would be meaningful to them and that they'd understand. If I'm in a room full of programmers, and I have a programming idea - the chances of me actually getting any unbiased feedback is pretty slim. If I bounce the same idea off of my wife, she's going to give me innocent feedback because she isn't affected by said idea and is only looking at it from an outside perspective.
