What should i do?

Ive done about 4 pregnancy tests. My last period started on july 9th and ended july 14th. Well I went to the doctor and i did a urine test and turned out negative. That was such a waste of my time and money. I kept telling the doctor my symptoms and how late i was and all she had to say was to come at the end of the month, of september that is. My period is regular and usually starts around the 8th through 10th but no later.  Now im getting mild abdominal pains and im not sure to just go to the emergency room. What would you do?