Preterm Labor?? Or Braxton hicks??

Alyiah

How do you know if you're in preterm labor or not? I'm 26 weeks 5 days. This is my 3rd baby - I lost my daughter at 37 weeks and 2 days in February- but bc I never felt contractions with my last 2 (I had them based on the monitors I just wasn't feeling them for some reason) how do I know. My stomach is uncomfortably tight and it I feel a lot of pressure on my hips and vagina (sorry if tmi) but idk when its considered labor and not Braxton hicks.