Chances of being pregnant?

Ok long story short, I am on birth control, (Nuvaring) and I took it out for the end of the 3 weeks so I could get my period. Yesterday was the last day of my period after getting it on Friday and my boyfriend and I had unprotected sex and he came in me. I put the ring back in today, a day later than I supposed to because I didn’t have my new ring yet. I was doing some research and it said chances of me getting pregnant were low especially because it was the last day of my period but I know there’s always that one possibility. But I was considering that since I’ve been on this form of contraception and my body has a schedule, i wouldn’t be fertile because there’s no ovulation. I just need some opinions lol