I 100 % understand that it's not easy and you may be scared of making that step even with supporting parents.
But we tend to imagine the outcome will be much worse than what it will probably be. And of course I don't know your situation and maybe your fear of a bad outcome is fully justified.
If you are sure your parents are transphobic and you still depend on them, maybe you will have to assess when it's a safe moment for you to make that move.
I think the best thing you can do is to seek help from an affirmative psychologist to help you assimilate that no one should give up living their own lives for the fear of upsetting or disappointing others and help you find the best moment to safely start asserting your identity. If that's not an option for you because seeking that kind of help would still need to go through your parents, you can search for local or online LGBT support groups.