Advice?

Shanellie
I've been contemplating sharing but I feel like I have nobody else to go to. I'm 16 years old going on 17 in April and I've only had sex twice: when I lost my virginity last month, and last Friday, both with the same guy, both times we used a condom. The first time was vaginal and on top of wearing a condom, he also withdrew before he finished and that time my period came two days early. This month I am already two days late but this time we had anal sex and it was 5 days before my expected period start date (I make sure it's a good couple of days after my fertile window ends according to eve), as was the last time. I feel like I'm just being paranoid because I've always considered my period to be irregular anyways since I first got it at 10 years old, which is why I got this app (to get a kind of idea as to when my period is going to start). Even now it doesn't really start when eve says it's going to so I just use this app as a guide to be ready. I just really wasn't worried about it until I became sexually active. I'm going to tell my partner that I want to take a pregnancy test to keep him aware but I feel like I'd be that one person to get pregnant from protected anal sex 🙄 Is there any advice that I could hear that could help my situation?