start date changing

i’ve been on birth control for a while and before my boyfriend and i started having sex my period would come the morning after i took my third sugar pill. ever since we’ve been having sex my period won’t come until later in the day (still after the third sugar pill). it makes me nervous even though ik for sure i’m not pregnant because he uses a condom and doesn’t cum in me. idk why it’s doing this or what it means (if anything). should i talk to my doctor about it and consider having my pill changed or just leave it?