Welcome to HCM
You have taken Emergengy contraceptive
pill within 72 hour of exposure,but as you missed period and urine test is positive .
Your case is failure of pill,so now you should visit a Gynaecologist and explain her your condition and see if it is possible with prescription drugs.
Otherwise you have to disscuss surgical (S&E) with Gynaecologist.
Please do not take medicine by yourself.
Good Luck to you.