If you have irregular periods, please respond!!

I had sex last Saturday with my boyfriend last Thursday while towards the end of my period... (I know you're probably thinking "eww" and I don't blame you, lol. ) But shit happens! Anyways he came inside me.. Like a lot! And everyday afterwards since we have had sex which he came inside every time. I am on birth control only to regulate my cycles. I've read and heard that it is pretty possible, I can get pregnant. My boyfriend has also told me that he says that his doctor said he has "super sperm" ... And a high sperm count.  He told me that because his kids mother was also on birth control and she got pregnant. With that being said, given the information I have been given, how possible is it that I'll get pregnant?