Confirmed pregnant but had my period, went to the ER they said I'm not?

I'm sorry to say it sounds like you just had a miscarriage not a period. Same thing happened to me when I had my miscarriages. It does sound like you were pregnant, especially considering tests do not give false positives unless you are on certain meds (fertility meds mostly). I highly doubt you are still pregnant, unfortunately. Best of luck to ya!