Pregnant?!??

Kmaj
I'm 20 years old
I missed my period last month. And I had recently lost my virginity so I thought that was why, I took three pregnant tests, 2 positive but they were cheap and one negative.
this month at the time that I was supposed to get it again I was cramping very very light and I spotted for a few days. 
I don't have sore breasts but my mom says they look fuller when I visited her recently.
Is something wrong with my body?! Since the expensive pregnancy test said I wasn't pregnant.