Am I pregnant?

I had u protected sex once on April 19. It was stupid of me but I was pressured into it. He pulled out but still...Now I’m noticing brown discharge in my underwear so I just took a pregnancy test and it says that I’m not pregnant. My period isn’t due for another 7 days so it’s not my period. I’m freaking out because i’m only 18 and if my parents find out..i don’t even know. And if i need an abortion I don’t even have the money for it