At last  

  a clued up GP  
 
 as stated, at an early age you need to protect your heart and bones.  HRT can help with this.  As can regular weight bearing exercise, a good diet, 'me' time and as much fresh fruit and veg. as possible.  There is a search button here so any queries you can press that 2 C if there are other similar threads.  Ask away.  
Your GP may well send you for a scan of your womb to check the lining 'depth' before beginning treatment.  Let us know how you get on.