What Causes Frequent Urination And Sore Breasts?

hi doctor, how are you?...pls help me out. i av a problem and i want u to help me solve it. i think i'm pregnant, cos i go to the ladies frequently and i've got tender and swollen breasts. i'v gone for 4 diff ultrasounds but they see nothing growing inside me.......pls help me doc. i'm confused.