Please Help?!?!?

Hi i haven't had my period since december 07 i have been to the doctors and had a urine pregnancy test done and a blood test done which both were negative (when i was pregnant with my son it didn't show up urine tests must have spent about �100 on every make you can think of, i was sent for a ultrasound and blood test and the ultrasound confirmed i was pregnant so i never got the results from the blood test) i had my son on the 29th june and 6months later i had a termination under cirstances i do not wish to talk about (so please no harsh comments, its me having to deal with wondering what my child may have looked like) i had a period after the termination but then they completely stopped! I have no symptoms of PCOS and im not very active but not overweight and im only 19 so not going through menopause and im a very chilled out person and not stressed at all! Sorry about the essay lol just wondering what everyones thoughts on here was?!?!