I understand exactly how you feel.
I have had many problems like yours and more since I was 12 when I first started my period as well.
The doctors have kept putting me off and saying that I am too young, but I live in constant dailing pain.
I have had surgeries and medications, etc. that have not worked. These issues run in my family when the women are young so you would think that my doctor would listen to me.
I posted a message to another girl similar to this but the message messed up when I was posting it so I don't know if it went through.
I just want you to know that you are not alone and if you would ever like to talk then just write me a message.
Jessica