Can I be pregnant ?

Okay so I think the last time I checked that I logged the last time i had sex was March 15 with it said my chance of pregnancy was 7% which I don’t remember having sex that day since on March 14 I hung out w my boyfriend and I said no sex bc I was full on my period. But maybe I did idk. I do remember having sex on the 19th which I checked and it said I was ovulating. It was protected sex and we always check the condom did not break. I got my period early March, had sex a little later in March like I said. I also got my period on April 4th. But recently ive had weird pains in my stomach and my boobs have been tender sometimes these are the only symptoms I’ve had, but can I pregnant? I’m terrified I’m only 16. My period was supposed to start on the 4th (yesterday) but it didn’t come. I’ve been trying not to stress about it either.