PI had sex for the first time 3 days before my period was supposed to come, and did not use any protection. I did not let my boyfriend finish because I was very nervous and asked him to stop so he did and he said there was nothing to worry about since he did not get to come. But I'm still very worried I have heard that you could get pregnant from pre-com. And my period did not come the day it was supposed to. I had sex on the 24 and my period had to come on the 27 but until now I have not gotten it, its 4 days late.My periods have not been that regular in the past few months. Could I be pregnant or just paranoid

Pregnancy is possible any time you have sex, and yes, there is more than enough sperm in pre-ejaculate to get you pregnant. You can use 3 different forms of birth control and still get pregnant, so having unprotected sex, like you did, is definitely a risk.

Wait until your period is at least 2 weeks late, then test using first morning urine. If that test is negative then wait until your next period is due, and if you miss it, test again, or get a blood test done at your doctors office.

The only way to prevent pregnancy 100%, is no sex. If you're having sex then you have to be physically, financially and emotionally prepared to have a child, because it can and does happen.

Good luck.