I need opinions

Alex

I’m 16. So I’m pretty sexually active with my boyfriend, and we always use protection but sometime this month and last month we were teasing and for a second he went in without anything but for like 5 seconds, which I know is still bad because possible precum. I’ve been feeling very nauseous and have headaches which are my period symptoms and I’ve taken at least 3/4 tests all saying clear negative between that time but my period is due in 3 days so were they accurate? And is it very likely that I’m actually pregnant or should I stop stressing?