I know you're 16, but don't say "smash."

I'm a gentle guy, and I don't see myself as being super dominant. Is this an issue?

Does this girl know it's your first time? She probably won't be expecting you to be James Deen or anything.

In general, I find women like men to be dominant in bed. So it may be an issue down the line. But don't worry about it right now.

If you want to be a good lover, just be willing and enthusiastic. Be attentive to her needs. Go down on her, if she wants that. Try to get her to orgasm before you do (or until she pulls you on top of her).

I guess my main question is: will sexual arousal make me 10x more confident and turn me into a machine?

No, it doesn't really work that way. Being dominant in bed is a mindset. It doesn't just "happen" unless you allow it to happen and are confident with your relationship with your partner.

EDIT: Let me also point out that I have not fapped in like 3 weeks so my testosterone is gonna be at unprecedented levels.

You should probably fap. Otherwise the act might be done in about 10 seconds.

Personally, I lasted a very long time when I lost my virginity because I was nervous. But if I hadn't masturbated in 3 weeks I feel like that might have been a different story.