I'm sorry you are experiencing this! I'm surprised she takes calls in front of you during session and talks about other clients text priorities, etc. I don't know the precise ethical rules, but at the very least she's being unprofessional and insensitive doing that. That is your session with your T, your time, your dollar. It should be all about you. You have every right to be upset.

As for her not answering texts, does she have a policy on that? You said she answers some clients but not yours. That seems unfair and unprofessional.

As a dietician, she is not helping you. You deserve better.

If I were in your shoes, I'd ask for help. I'd ask for referrals for a new T and dietitian.