Weird cramping?

Sammy • Soon to be 21, been a mother to my little man since age 16. I am engaged to the love of my life/highschool sweetheart & we have our miracle girl on the way! Due St. Patrick's Day!
I'm not due for period until four days. Weird pelvic / uterus cramping that isnt sharp or painful.. just uncomfortable. Bloaded with gas. Last two months my period has been light for 3 days. The norm for me is heavy for 7.. any idea? I took 4 tests and all no go.