19 week late period but not pregnant!?!?

If you were pregnant and far enough along the doctor would be able to tell by your hormone levels. Considering you may have pcos - you could possible have a cyst that is about to rupture which may be causing you some pain or discomfort. It's very common for a woman with pcos to go months without a period. There really isn't one definitive test for pcos. They can check your testosterone levels but considering your weight I would imagine it would be higher no matter what. I would go back to the doctor and get a pregnancy test one more time and then ask to be put on birth control - make sure they put you on a pill appropriate for someone with pcos - I believe apri is good one for women with pcos. But you really need to some what regulate your periods. It's not healthy to go nineteen weeks without a period.