please help.

i have a ongoing problem that i would be releived if u could give me an explaination, as my doctor doesnt really seem bothered about this as he says i should look into this when i want to start a family.

i started my periods when i just turned 12 and where regular every month with a normal flow until i reached 14 my periods just stopped, after 8 months of nothing happening i went to see my doctor who put me on the pill to help stimulate my periods, this worked for about 2 years then i stopped bleeding again even on my week break when i should have a withdrawl bleed. this continued for abt 6 months so i went back to my doctor who advised me to come off the pill and let my body get back into its natural way of things, he did explain that it can take anything up to a year for my body to get into the natural way of things, having been off the pill or any method of contraception for 18 months, my periods have failed to return, my doctor has proformed blood tests and set up an ultra sound to see if there was anything wrong with my ovaries and my horemone levels and everything came back with normal readings he even put me on a 5 day course of horemones to see if i would have a period after stop taking these, which only i got small amount of spotting that lasted a day. i have been having very regular unprotected sex with my partner for over 18 months and i havent got pregnant. there is times in the month for a few days i can be emotional and on edge with my normal cravings, i have no family history of this happening on either sides, infact both sides of my family are very large families please can u help explain what is wrong, and why my periods havent returned.
having children has always been my lifetime ambition, am i able to have children naturally or at all?? please help me, i am getting worried about this now and my doctor doesnt seem to be taking me seriously. please help id be soo greatful

from sophia