I can tell you that having had even limited unprotected anal intercourse with a person on unknown HIV
status, you did place yourself at risk for acquiring HIV
. Unprotected anal intercourse is the riskiest of sexual activities. However, as the "top", you were at lesser risk than your partner. That the insertion was brief also bodes well for you.
Now that you are on PEP, that does extend the testing time to a final, conclusive result.