I lost my virginity recently to a much older girl. First she gave me oral sex with a condom as foreplay, then we had vaginal sex with the same condom. The condom stayed intact the whole time. It did not slip or rip and had no visible holes. However, is it possible that her teeth could have made microscopic holes that would have allowed HIV to pass through? This is the only sexual encounter I have ever had. I'm not even sure she had HIV. Seems like I'm thinking of the worst possible scenario and there's constantly a lingering voice in the back of my head saying "what if", it's causing me to worry. Am I being irrational?

In short, yes, it sounds irrational. Since you are now sexually active (or at least probably want to be!) you need to keep using condoms and have an HIV testing plan for yourself. In the meantime, you might want to think about other reasons behind your worrying. Perhaps guilt or anxiety? A counselor or trusted adult might help you talk through any concerns you uncover.

-David