At least your step-mother is trying. If they are making statements like "can't be that messed up", then I would think that they will never be willing to accept you. It's possible that they will try to make your life as difficult as possible. People like that aren't worthy of you, family or not.
As I've said in many posts before, I have cut all ties with anyone and everyone that I share DNA with. They are so bigoted against anything that "isn't normal". To them you are either male or female and straight. Not transgender, homosexual, or mentally impaired. If you try to be (or are) any of that, they have a simple 3 letter word for you. It is typically a derogatory term for homosexual men. I'm sure you know it.
"There are only 2 sexes. You are what you are born with. Accept it, or kill yourself because you are a freak. Also you have to be straight. If you're not, stay the hell away from my family. I don't want you to spread your (expletive deleted) to my family."
That was a speech by my aunt. Does that begin to describe the severe bigotry I grew up with? I'm sure other people here have gone thru the same.
So if you're really connected to your family I would say to be patient. Also try to tolerate the ones that are dead set against it. Unless they try to harm you in some fashion other than verbal attacks. Verbal attacks can often do more damage than physical, but don't just pick up a bat and go on the attack. Try to hold back your rage. If you flat out lose it, you may harm yourself more than you harm them.