Guest post by "z" @Rachel- you think she's a trans girl, not a trans boy? I see that as even less likely. Her mother is being portrayed as a violent person in this strip- I REALLY doubt that she'd be "too drunk to stop her". Drunks are hardly known for being incapable of abusing children. Besides which- she's clearly now in a situation where she's 100% accepted as a girl. Why would she so resent Sarah if she's in a situation where she's accepted as and free to be herself?
Also, I appreciate that you raised this point before the newest comic, but the newest comic completely disproves it: her parents are using female pronouns. They would not be doing that if she were AMAB.