Could I be pregnant? Any similar stories?

Ok so ive been on birth control pills for 3.5 year and it does a good job on regulating my period but lately over the past week I been having some symptons that seem like they may be pregnancy but im not sure. I just went to the doctors early last month for a pap so before go back to the doctors this month I just wanted to know if anybody else had the same symptoms. Im usually get gy easly after a meal but I dont really burp often. Since Monday I have been burping everyday even without eating anything all day, I have been having these weird twinges in my stomach and on my side and sometimes it feels like pulling, again even after not eating all day. Then I had a couple of really sharp pains in my and now they are more frequent but less painful and have been having lower back pain on and off all day. It also feels like I have mild mild cramps on and off through the day along with headaches that come and go quickly. I am so confused. I have taken a preg test and it said negative but it still could be to early. I must also mention I do once an awhile miss a pill but douple up the next day. My period isnt for another 12 days..........