Pregnant??? Or just over-thinking?

Me and my boyfriend had sex two days before Valentines Day, and I never worried about him doing *that* in me until now.. He said he didn't but I'm just scared.😭 I don't know if I should just wait and see what happens or try to take action and see what's going on.. Please help! I'm still in high school, and involved in cheerleading and many sports.. I don't think I'm ready for something like this yet..