hi!

ive been taking ortho tri cyclen lo for 6 months now with no problems at all. I generally miss a couple of pills here and there but double up the next day and nothing ever happens. This month I missed two pills on the 12th and 13th but doubled up and took two on the 14th and 15th to catch up again (as the instructions say to do). I had sex on the 9th 10th 11th 12th 14th and 18th all unprotected because my partner and I are both clean and birth control has proven itself effective. However, on the 15th I experienced brown discharge but it was very light, not enough to put on a pad or anything. It went away and came back on the 21st with breast tenderness and lower back pain. I have been taking my pills routinely since I missed the two and have never experienced anything like this since I've been on birth control..... do you know what is going on? Am i pregnant?