Hi Kim,
I don't have any really useful ideas on your GP appointment to offer
but just wanted to wish you luck and hope to goodness they can get you some relief.
Whatever you do, don't let them fob you off, this is a long time to have a normal headache, let alone a migraine. You must be exhausted.
I have my fingers crossed (not my toes lol, they are very burny at the moment - I blame this air pollution!).
Let us know how you get on x
Bram