I am 12 days after my first iui and 3 days late on my period. i was told by my doctor not to take a test until sunday 4/21/13. could i be pregnant?

IUI pregnancy: Implantation takes place within 3-5 days after fertilization occurs.But you won't detect any pregnancy hormones until 10- 14 days after the iui. Taking the test early may lead to a false negative test. I would follow your doctor's recommendations and do not stop any support until instructed by your doctor.

Also: Also if he forced ovulation with HCG (pregnancy hormone) you can get a false positive from the injection.