Possibly pregnant again?

I’m 11w PP, I have not had a normal period since having my baby. 2 weeks ago I decided to take a test just to be sure because what I assumed was my period was really just 3 days of brown spotting. The test came back faintly positive, and I have been testing at least twice a day since then. Some tests come back faint positive like the first one I got, and some are 100% negative. The only time I get a positive is in the evenings, if I test in the morning or afternoon you can’t see anything on the test. Im sure I’m doing the test right, and reading the results 3 minutes after taking it. I don’t want to make a doctors appointment just yet because I don’t have health insurance, and I don’t really have $150 to give them right now for blood work. Can any of you give me some insight as to why I only get positives in the evenings, and how come the test line isn’t getting darker? Can I really be pregnant right now with how crazy the testing is going? I’m not on BC, we used the withdrawal method which I know isn’t a reliable source of avoiding pregnancy. I’ve been using the FRER, and Clear Blue. Both give the faint positives in the evenings. Thanks for any help.