Sounds like you need a new GP - if she is being obviously transphobic you should be able to complain, if you're in the UK the NHS have a fairly good policy regarding discrimination, even though not all centers follow guidelines.
Again, I'm not sure what it is like where you are, but you may be able to self refer to a gender clinic and explain that your GP is unsupportive and is refusing to refer you.
Good luck in finding a way around it - things should work out eventually.