Hi, Angeldancer,
And welcome to the forum!
Nandm said it best. Pot won't help your pain, and can contribute to depression. Furthermore, chronic pain will contribute to depression.
If you feel that your doctor isn't listening to you, please go get a second opinion. There are pain management clinics out there. Perhaps that's an option for you. But, living your life stoned isn't an answer for a 20 year old. Read the substance abuse boards and you'll see that for yourself.
I wish you well, and hope you'll find answers. Please keep us informed as to how it's going. We care.
Shalom!