Really confused woman here lol

My bf said he came in me but when i wiped there was no sperm like there always is, why? We have been ttc  for 9 months now and well everytime after we had intercourse and i cleaned myself there was his sperm but not this time ! After i wiped there was no sperm there so idk if he really came in me or i guess for the first time all the sperm staid in?? Im so confused please help..