PLEASE HELP ME I'M WORRIED AND DON'T WANT TO HAVE A BABY

Okay so it was my boyfriends and my 6 month anniversary today. I went over to his house for dinner and movie night. We ended up having sex 3 times. The third time I remember seeing some left over semen just above his dick but after he thrusted into me it was gone. I didn't think to much into it at the time (obviously my mind was occupied with... other things). The semen would have most probably be transfered to me, either on or around the clit, he took his dick out at one point to rub the tip on the clit (yes he was wearing a condom at this time). He then put it back into me and proceeded to thrust quite deep. If that semen did in fact transfer onto his tip right before he stuck it back into me, could there be a chance of conception? I am currently on no form of birth control and according to my eve calender today is my most fertile day (33% chance of conception). Am I just paranoid or could there be a chance of conception?