Extremely late period

So I used to be on birth control but stopped taking the pill about 5 or 6 months ago, incase that is relevant. I am extremely sexually active right now. I am 19 days late for my period, but I took 2 pregnancy tests at about 12 days late and they were both negative. Since then I have had period like cramps but no period still, I have been nauseated and tired, and I was spotting super heavily a few weeks ago when my period was expected, but it wasn’t my period. It didn’t look like a period at all it was like heavy brownish discharge. If anyone has some insight I would love to hear it as I do not know what other reasons I would be so late besides pregnancy. Thankyou!!