Confused???

I was suppose to start September 19th and my last period was august 16th, i still havent started and ive taken 7 pregnancy tests 2 with faint blue lines and the others saying negative, ive used cheap brands to the most expensive and im not having any symptoms of my period starting like i usually do. Idk whats going on but i go to the doctor the 11th im just confused bc my period has never been this late(except my first pregnancy i had sex on my ovualtion day which was oct 4th and tested october 17th 2013 and found out that quick i was 2-3 weeks pregnant so i am so confused about this if i am or not???? Can anyone give me some advice or has anyone gone through this same thing where 2 tests have very faint lines and then you take tests after that a couple days later and they say negative?????