Testing after PEP

Male, 44 years old. I had a brief 10-20 seconds unprotected exposure with a sex worker. Doctor said I'm at low risk, but I insisted on PEP. Started PEP 40 hours after exposure, never missed a dose. Tested negative two times with 4th gen test, first time 17 days after PEP, second time 24 days after PEP. I'm still worried and anxious. My question is, how likely is to test positive later? Does PEP delay window period and by how much? Should I test again? I also tested for other STD, all negative.