AHOY, uhh... I was meant to merit your previous post, the one that pointed out the age of the account. Sorry for the mistake, guys.
OP, I can't believe I spent quite some time diving and reading about gender reassignment procedure, but... doesn't the country you're at, whichever it is [though it'll be much appreciated if you can tell us which, so I can specifically focus my study on the rules and procedure following or prior to the... procedure] issue a formal document explaining the transition status and/or issue you a new ID that linked to your old ID?
Since your account is two weeks old and I am somewhat sure you've got reassigned quite a while prior to signing up to stake and stumbled upon this situation [as I find it hard to imagine someone will bother to play on gambling site during or right after the procedure, due to the post-surgery pain itself alone]. If you happen to have that formal document, it might be worth to try showing that to Stake to prove your situation. Or, if you have new ID issued to you?