chances of pregnancy??? 😱

Vanessa
my boyfriend and I are in a long distance relationship. we saw each other again for the first time in a month, and we ended up having unprotected sex several times over the course of 3 days. he didn't ejaculate in me, but I'm sure pre-cum must've gotten in. We intended to use protection (namely condoms), but we didn't for the majority of the time. stupid, I know! I'm terrified of getting pregnant, what should I do?? is there anything I can do to prevent the fertilization? it's so difficult to get Plan B. pls help
facts to consider:
I'm 17, almost 18
this was my first time
I have an irregular cycle 
I think I just started ovulating today 
I had sex yesterday and the two days before