Could I still be pregnant?

It's almost been three months since my last period. I took 8 pregnancy test and they all came out negative. I even went to Rachel house and got a doctors strength pregnancy urine test. That also came back negative. I'm rlly confused lol. I have no pregnancy symptoms at all. What reasons could there be besides being pregnant? My periods are always regular and always on time. I'm having my mom take me to the doctor. ASAP , but any ideas on what's up? I'm 16