Is The Blood Seen Only On Urination Indicate Pregnancy Or UTI?

I am a female.I had unprotected sex on May 14 using withdrawal method. Since then i am having abdonminal cramps and i thought it is because i am worried. My period is due sometime this week but since yesterday i notice blood on the toilet paper everytime i wipe.I thought it was my period so i wear a sanitary napkin but no blood appear on it, its only when i urinate. Could i be pregnant? Is this UTI? Awaiting your response.Thank you