Re: Worried after 9 months exposure to HIV+ girlfriend
It's not confusing at all. PEP slows viral replication, and the normal window period is 3 months, so you need to test at 3 months after your last dose of PEP to account for the effects of PEP.
If you want more accurate results, you can have 4th generation testing (DUO) which tests for both antigen and antibody. A DUO 1 month after PEP would be highly encouraging. You would still need to follow up three months after PEP with an antibody test.