Period 2 months late but negative pregnancy test?

I’m at least 2-3 months late for my period. My periods have never been on time but before missing this period I was pretty regular. Always a few days off maybe a week at most. I’ve been feeling very bloated for ages and I’ve taken a test and it was negative. I don’t know what to do??? The doctors will probably just say I’m “stressed”. Anyone got any answers to why I could be so late but showing negative on pregnancy test???