I really hadn't planned on getting involved in this one, but here I am. Another member actually PM'd me last night asking if I could maybe give my thoughts on it. I hardly know where to begin.
Its a shame you were sheltered as a child, that leaves one unprepared for many things in life. Developing
"social skills" as we grow up is almost as important as the textbook knowledge of education. Hard knocks 101 is also
very needed, we can't shelter to much if we do nothing is learned. Life isn't roses and wine.
I think you need to just stop thinking
"her" that would be a start. I think the nervousness sets in immediately at that point, then panic. Think "possible friend" when talking to anyone. Since you say you don't talk much, then I have to assume you're a good listener. Use that, it will help guide you to topics of conversation. In listening you will find topics.
Don't act like you are interested in something you aren't really to make points with anyone. It will be detected and is a turn off. Stay "online" but lead to a similar subject that could be continued. If it fails bail from that and talk of something in your surroundings. Like if she/he talks of baseball and its not your thing, admit it. "Sorry I don't know much of baseball, but I do follow basketball. Do you? "If she/he does run with it but let her/him talk too, if she/he doesn't move on. If you're at school bring up something going on on campus, at the park "Have you heard about the proposal to ban dogs from the park? (or any local stuff) Relax and let it flow.
I really feel you think you have lost before you start and therefor panic and don't put forth a real effort. To "not try" anything because you feel you will fail is a sin. Nothing beats a failure but a try is the old saying. You would have never said "I can't" in my mother and fathers home about anything."You better always try hard, never stop trying, always give it your best and you will spend you life surprising yourself. " my mom used to say. Relax, take baby steps you can do anything. Your failures are only things "you" give yourself. So why not reverse it and give yourself "successes".

Its all there inside of you, find it and shine.
Note: Maybe no laughter watching the movie because she had things on her mind, something bothering her. Did you ask? Doesn't mean she was bored. The walking her to the ladies room and waiting outside the entrance was
100% the right move. No fault there on you, I had a date do that at the football stadium once, I thought it was the best of manners and was very impressed.
Good Luck
LL