Help please

Has pcos caused you to get false negatives on a pregnancy test? I’m worried that that is what could be going on with me. I’m worried that I am pregnant and it keeps coming back negative because I may have pcos. I have never gone this long without a period 😔 It’s been 3 months. I have bloating and cramping. I’ve taken like 20 pregnancy tests, the last one being a little over a month after having sex.

This morning, I had brown stains/spotting on my underwear. I don’t understand anything😔 Could it be possible that I ovulated so late that I just got enough hormones to show on a pregnancy test? After a whole month and some days of testing?

Please help, I’m 20, I can’t stop worrying. Has this happened to anyone?