One positive; three negative.

5 months ttc. Got a positive test today. Took three more and all three negative. I'm feeling hopeless and stupid for believe the first test was true, after months of negatives I shouldn't of gotten happy over one positive test. My period doesn't start for 6 days. But I was feeling strange so I tested early. 
Anyone else start questioning all you're doing to get pregnant when it's been months. I know it hasn't been long but I got pregnant with my 3 year old the third time of unprotected sex.