>>1
Personally, I've never had an orgasm when I've been nervous or stressed, in spite of that my fiance is damned good in bed and normally is great at getting me off.

>>2 says very wise things, including the thing about unsafe sex.
Don't have unprotected sex again, please.

>>4
You are supposed to get pleasure from giving, yes, but also from receiving. If you're too hellbent on being 100% certain of giving really well, you'll be too focused on that to get off. I know this from personal experience.

As said, focus on having as much fun together with your partner, and not on getting either of you off.
You may find it boring, but try to get to know your body well by yourself, so you can help him with getting better at doing all the right things for you, and thus making the experience more fun for both of you.