Late Period, Negative Tests still feel pain

Patient: Good Morning,I am 23 years old. I am overweight and have been for many years, nothing too crazy and have never had any health problems due to my weight. Last month my period was very light, lasted 4 days and only required a liner which is very unusual. This month my period is late I am 4 days late now, I have regular periods. I took 4 tests 3 of which in the morning and have given me negative results. I have been feeling nausea during the afternoon or right before I get hungry. I had been experiencing some period like cramps but they the pain has now moved to my lower abdomen. It feel like pressure on my bladder, like when you hold your urine but I have no need to urinate. I was wondering what might be wrong, I will go to a doctor this weekend but I am concerned.

Symptoms: Nausea, pressure, cramping, late period