False Positive :(

Hello all,

This is my first time posting. AF was to come on 11/17 And when she didnt show I took a test and got BFP! We were elated. Fast forward to Friday 11/24 I started to spot and cramp a bit. I got worried as it became a bit heavier. We went to the ER and after taking my blood and sonogram they said I was not pregnant and was actually getting my period -37 day cycle. I have been pretty irregular ranging from 28, 35 and 37 days. What a roller coaster of emotions. Has anyone else had false positives?!