Suggest Treatment For Irregular Periods

Hi about three weeks ago i had unprotected sex with my long term patner and took the morning after pill. a week and a half later i had a period. two days after i finished my period i felt the constant need to urinate although hardly any urine was coming out. I also noticed i was bleeding in my urine. The doctor diagnosed me with a UTI which they gave me a three day long course of antibiotics. From my knowledge the UTI has cleared up as i dont feel any symptoms and the bleeding stopped. Last night me and my partner had Sex but we used a condom... this morning i found i was bleeding very lightly from my vagina. What could this be?? I am worried as i am not sure if the UTI has returned or if I am pregnant. I also suffer from very irregular periods. Mainly I have a period once every six months if that at all. So having two periods in one month is abnormal for me.