I'm starting to get concerned

I haven't had a period since July 12th, I have missed 2 periods as of today and I'm not sure what's going on. After the first few weeks of being late, I took a test I laid it down and came back 5-7 minutes later, it showed a faint Positive. I was extremely happy as the line was there plain as day, to be for sure I went to the store and got another test for the next morning to confirm and it was negative . I have taken 3 test since the faint positive and all read back negative. I don't have a medical card so I can't go to my family doctor and I really don't want to go to the er and get a medical bill as I am unemployed. I've always had someone off periods, but never this far apart, usual 1-7 days Tops I would be late but not 2 months. Opinions? Please help me.

P.s, I use the .88c hpt