Hello, and I hope I can help you today. If you are on birth control, and you did not miss a dose, there is no reason to assume you are pregnant especially if all of your pregnancy tests have been negative. Over-the-counter pregnancy tests are extremely reliable and can detect pregnancy hormone even if you have not yet missed a period. Many hormonal contraceptives can cause symptoms similar to pregnancy as side effects- like bloating, breast tenderness, spotting or brown discharge, nausea, cramps and mood changes. The twitching you feel in your abdomen could have other potential causes, but women do not feel fetal movement from a normal pregnancy until they are at least 4-5 months along. Lower back pain can be a symptom of a bladder infection, so if you had one recently it would be good to see your physician back so your urine may be checked to see if your infection has cleared. If you are having side effects from your contraceptive that you find disturbing, you may want to discuss an alternate method with your healthcare provider, but again, your symptoms are likely caused by your birth control and a possible bladder infection rather than pregnancy. I hope I was able to adequately answer your question today and that my advice was helpful. Best wishes, Dr. Brown