I am a 20 year old gay man, and today I had anal sex with another 20 year old guy - I was top. About 5 minutes into the act, while trying add lube I suspected that the condom broke. I immediately changed the condom and we continued to do our stuff. After we finished everything, I checked the old condom and the condom was in fact broken. From what I felt, I believe the urethra was exposed (I don't know for how long).
After the act I checked again with him that he did not have HIV, to which he replied that he does not have. But since it was a one night stand I don't know if I can trust this guy for 100%.
After getting home, I checked for any cuts on my penis and found none.
Additionally, it is important to say that the sex wasn't that rough.
I read that for Top guys, the risk is lower, but I am really freaked out and want to know if there is any reason to worry? Obviously, I will go and get checked, but from what I understood I have to wait 3 weeks before it can be discovered.
So, Should I be worried? and What are the chances of transmission considering I was top?