Scared...

So, my boyfriend and I will be together for a year tomorrow. We are both 20. Well up until yesterday we were both still virgins.. (We kinda still are) we attempted to have sex yesterday neither one of us knew what to do.. His penis literally got in me for like 3 seconds, and that's it... Well when we pulled the condom off we realized there was a little bit of cum in it. I can't be pregnant, right? I'm so stressing myself out over nothing probably..