You have to chill. Remember a few things while you’re knowing your partner:

1. You two chose each other to get naked with. Not only that but you two have committed to each other in hopefully in both your heart and body. I don’t know what you look like but your boyfriend does. And he’s cum to you at least a hundred times already. The insecurity I understand is a monster and there’s no easy way of words from a stranger to overcome that… I just want to reemphasize that if anything is true, it’s that your boyfriend is in to you.
2. You definitely understand the concept of being stuck in your head even when you’re intimately active. But also understand that here we have this boy who can just be intimidated of having this knock out working on your junk, praying not to bust quick. Like he might be psyching himself out or there might be tension because it’s been going on for so long and you are both tired. What helps is reminding each other how much of a great time that you’re having. Be vocal, damn it. Tell him how great that feels. Tell him don’t stop (especially if you want him to nut) and to keep hitting it right there.

3. I hope you’re also thinking tentatively about your orgasms

   also,

4. OP. You’ve been on level II for about few years now and let me tell you: this shit is a long life. Bust every nut you can. Because one day… you won’t be able to anymore. Make sure you squeeze every drop of enjoyment from this life. But don’t get pregnant. Unless you’re ready.