I'm panicking

Me and my boyfriend recently started having sex, I was a virgin before so I'm a little new to this and have high anxiety so I know this sounds silly but I'm very very scared I'm pregnant. On Easter the condom broke and I took plan B and we've had protected sex since then~ I always put the condom on for him cause it makes me feel more comfortable and a few times some of his precum has gotten just a little bit on my hands~ I continue putting the condom on and made sure to avoid touching it and it never feels like I got any precum that was on my hands onto his penis so I think I'm fine~ but Precum would be the only way I've gotten pregnant, today I had protected sex but it's a fertile day and that really scares me (I'm getting the depo shot two days from now) I've been getting cramps for a while but I might be dehydrated or something, I thought the cramps were my period but the app says it's not due till the end of the month~ I'm really really scared, I'm only 16~ what are the chances I'm pregnant? And please inform me about precum! I'm so so stressed~ I can't get pregnant~