First response false positives

I’ve been getting faint positives for about a month now, hasn’t gotten darker. Some tests come out negative and then they come back positive the next test and it’s been going on and off like that. I don’t take any medications and have no infections so idk what could be causing this to happen.

Adding on:

I have gotten blood work and said it was negative. Went through scans and urine testing at the hospital, and was told nothing is wrong with me and that I’m not pregnant. I’m also late on my period.

UPDATE: I did end up going to my doctors and she said there’s no reason to do bloodwork again because the hospital did it already weeks ago. She couldn’t explain why I keep getting faints but says my blood HCG levels were just under 5 and that makes it non-viable, and that if I was pregnant my levels would’ve risen and would be making the line on the tests darker by now.