I think there's a lot of room for misinterpretation with texts/emails and tone, and it seems like some Ts really work to keep contact outside of session very brief. As for the 10:30 thing, maybe she offered the time slot to someone else thinking it was open since you had changed. Hard to say what the reason is but I'd guess it's nothing to do with you.

If you're having trouble talking about something in session that you feel needs to be said, have you tried writing it down in advance? Then you could maybe read it to her or have her read it, and you'd know the information got across even if it is very difficult to discuss.