sex/condoms situation

Okay, so I'm 16, and I had Sex with my boyfriend on Friday, this was the third time that we've done it. All three times we've used condoms, but on Friday, when we stopped having sex he cumed on my stomach, and I'm worried I'm pregnant! - I'm not sure when I last had my period, although I'm pretty sure it was around 4 weeks ago! - I have exams coming up so I'm pretty stressed, but now I'm even more stressed because now I'm thinking shit did the condom break or something? - we checked around 4 times to see if it had broken and he said it hadn't and I felt it and it didn't feel like it had, but I don't know. Please someone put me at ease!