You don't sound like you're being a mess, those sound like perfectly natural feelings when you spend such emotionally charged time with someone and you feel like they have a more fulfilling life outside of session.
The truth is that T's life probably isn't as perfect as you imagine it, and also that she wouldn't be able to be emotionally present for you in session If she didn't put time aside for self care.
But your feelings are totally valid, and a lot of clients feel that way. It would be a really good idea to talk to T about these feelings and perhaps explore how weekends could be more fulfilling for you.