Has anyone got a positive then negative and end up pregnant??

Saundra
Ok so I took a test yesterday fmu and got a faint positive. Then later into the day with a different test a negative. Then even later into the evening I took 3 tests one was the same as fmu and 2 different one and one was positive which was a different brand and the other 2 negative. Took one this morning, I'm not sure if you'd consider it fmu because I got up at 6am to pee, but it was negative. 
If I am pregnant I'm no more than 4 weeks, and I still think that's too far along. What do you think??