So I work in a retail store that deals mostly in childrens toys and items, and no matter what I do I can't seem to pass in the slightest; it's my voice, face and figure, the three things I can't change by myself

At least twenty times a day I hear 'give it to the nice lady so I can pay' or something else along those lines, and it's killing me. I've recently been shot down after being so sure I was about to start T (was told twelve months instead of a day later that week) and everything is combining together to bring me right down. I used to mentally refer to myself as male, using male pronouns and thinking of myself as a guy, but now my brain has switched back to refering to me as a girl, and every time it happens and it comes from my own thoughts reflexively, I'm left kicking myself and feeling even more misserable.
I'm just wondering if any of you other guys are in the same boat? If so how do you stop it from getting to you so much? Every time I hear 'thank the nice lady' it makes me want to scream, or maybe hit something. I cracked my knuckles on the wall in frustration/anger in the back room the other day and had to come to terms with the fact that I'm really not coping.
Help please