what does preterm labor feel like?

Destiny
Hello, I am 31 weeks 4 days pregnant with my little girl. I am at high risk for premature birth due to having type 2 diabetes prior to becoming pregnant. My glucose levels are pretty under control with meds. For the last 3 days I have been having pretty bad abdominal pressure and cramping and constant lower back pain. It was bad the first day it had me in bed almost all day, yesterday was better I was able to clean up my place and make it to my ultrasound appointment, my doctor said everything looks perfect. I didn't ask about the pain because well I wasn't in pain then and thought it was just the baby moving into position down wards. Last night and this morning the pain is back and even stronger. I don't think I am having contractions no spotting or leakage that I can tell. I don't know if I should go into L&D or just relax today.