She said she'd still love you, but you never truly know how someone will react until you tell them. People like to think positively about themselves, so of course they'd say they'd react in a positive way ("I'd still love you"). Some things are just too shocking for people to react in a positive way, though. You never really know. So, even though she said she'd still love you, I'd be cautious in telling her.
Anyway, I definitely wouldn't tell her if you're not 100% sure you're TS. And she probably doesn't suspect anything, since you two were already on the subject of transsexualism.