How do I know if I'm definitely pregnant, what do I do?!

Lisa

I'm 15 and I've lost my virginity to my boyfriend, who we've been together with for about 5 months, about 2 weeks ago and I don't think it was a good idea, at the start of this year I was so scared about even kissing someone let alone having sex with them but this boy wanted that and I guess at the time i did, it wasn't the first time, the first two times we used a condom but this third time we didn't have one and I'd been taking the pill but I don't think I did properly as I missed one and 2 were taken late and I was on the week break so I don't definitely know if the pill worked or not, I may be pregnant and I don't know what to do