Preterm labor scare

Okay I need some mamas help I’m a ftm and don’t know what a contraction feels like, I went to the hospital for side cramped and they made me stay because I was having contractions they stopped I was sent home now I’m terrified of going into preterm labor I have bv currently also so that doesn’t help and I’m still getting “contractions” my stomach tightens up weird but I have no clue how to tell if it’s a real one or if baby just moved weird also I’ve been having period like cramping maybe a little wors today any advice and can anyone tell me how they knew they were going into preterm labor