I have not had a period for two months, but the blood test and ct scan all came back negative. i have pregnancy symptoms what could this be?

Hormonal problem.: There are many hormones that contribute to normal menstruation. I would advise repeating the pregnancy test, and then having a thorough pelvic examination with a gynecologist. If that is all normal, there are other hormonal problems that stop your periods. Some relate to a gland in your brain called the pituitary, though this is rare.

Why a CT?: If the ct scan was of anything other than your brain i wonder what they were looking for? At your age i would not be suggesting a ct scan of the abdomen or pelvis unless it is targeted at a specific finding. Us or MRI would be a better choice in the diagnosis for the pelvis.