Nuva ring / pregnant

I am 18 1/2 years old and am on nuva ring i leave mine in usually all 4 weeks and then switch but it says my period was a week ago and every night I wake up with these terrible cramps in my lower abdomen, I get up use the restroom and then normally feel okay then get up and do the same every night about 3 times. Over a year ago at 17 I had an ectopic pregnancy, so that's always a concern and worry for me but I never had these symptoms like a regular one, last Sunday I took a test and it said negative. Is it just what I'm eating or could I be pregnant???