Period or not ?

Hi everyone ! I’m 17 and on the pill and have been for a while and I am sexually active , I take my pill at the same exact time every day and he pulls out every time. We’ll he has pulled out ejaculated and wiped it off and put in back in. Today I was supposed to get my period. Well I got it this morninv it was very light and now it’s just seemed to be nothing ? But it was a very light period. Clumps and all. What could be the cause of this ?