Reading this article I find myself ticking a few of these boxes so I will be looking up Highly Sensitive People's later, thank you for bringing it to my attention.
As for the sex side of things, I'm gay and very randy, I could have lost my virginity a full year before I did but I chickened out because it would have been a threesome and I was terrified of someone watching me having sex for the first time in case I did something wrong.
When I did lose my virginity for the first time the sensation was VERY distracting. He kept asking me how it felt and I kept replying "it's different." Of course it was different it was an object entering my arse, I'd never felt THAT before. He did not like that answer after a while, I must have said it a lot of times because he half angrily said "stop saying it's different".
That sounds bad but after he sped up a little and it stopped feeling different and started feeling kinda good. He came, and jerked me off. The next morning, I was ready, I knew what to expect and I wanted to try it again. This time it felt really incredible, I wasn't distracted by the unknown.
If your nervous you need to find a nice guy or close friend and like that article said to explain you can find new experiences distracting and you might need time to process the new sensations (and you'll be more enthusiastic during round 2).
I met a nice guy and just dived right in. I could have done with knowing about the possibility of being HSP and giving him a heads up but we muddled through. We dated for two years after that and fucked like rabbits whenever we could get together. It was GLORIOUS!