Okay so I've been having issues with my period recently. I'm probably stupid for still worrying about this but eh. 

I was fingered on October 23rd, 2012. I think he had precum on his fingers. I got my period mid November and it lasted for 4 days. I got it again in December and I stopped taking birth control after that because it lasted an entire week and was extremely heavy and painful for the entire week. 28 days later I got my period again in January and now (according to my period calculator app) it's almost 3 weeks late. I'm having dull aching pains in my ovaries and lower back. I went to my doctor and they didn't do a pregnancy test but did do a urine test that was slightly positive for red and white blood cells. The nurse seemed to think I have a UTI. Why would my period be so late though? Ugh. I'm getting impatient. I haven't had sexual contact at all since October. I don't think I'm pregnant (because I took 3 tests the week after it haopened in October and all were negative, including a doctors test), but it's still worrying me. Why is it so late?