Unprotected sex while on birth control and light bleeding

I am 18 years old and have been sexually active for about 6 or 7 months. I've only been with one guy, and after about 2 or 3 weeks I went on birth control. I had two UTI's in the first 3 months but never got them checked out. A week ago I was in so much pain I had to leave school for a week. I went to the doctors and found out I had a bladder infection. I got medicine and am going back for a pelvic exam. I have unprotected sex with my boyfriend everyday but whenever I urinate, there is light red blood? Also, a week ago I randomly got my period even tho I'm on birth control. It was dark brown and heavy in the mornings. I figured it was all due to the bladder infection but will the placebo's work on my birth control now? What is wrong with me? Please help.