I am so glad you are taking what I'm saying as supportive of you, because that's exactly my intention. 
So, I hope you don't mind if I get up on my soapbox, in response to what you said your T would say.
This is something I feel extremely passionate about. And as your T would probably point out, I am not a T. But I AM a parent, so I've experienced attachment needs from that viewpoint. And I also experienced them as a child and know how that went for me. So here is what I've learned.
One of my children is an extreme extrovert and had no problem with separation anxiety. My other child is just the opposite, and was very fearful as a young child about going into new situations. She would frequently not want to go into any kind of child care or parties...and although I invited her to go, encouraged her to go, showed her how much fun she'd have, I never MADE her go. Instead, I made it clear that she could always stay with me if she wanted to. And she often did. There were times this was inconvenient for me, and times when I got "those looks" from the other parents, who believed along the same lines as your T seems to, that the way to build trust is to "force" children into situations where they have no choice but to "trust".
But IMO, and IME (in my experience as a child, where my parents were reliably not available), those children don't learn "trust". They simply learn to be quiet and accept that their parents WON'T be there for them. This may LOOK like trust, and it's convenient enough for the parent, but really, what other choice does the child have?
But I wanted my daughter to build that secure base with me, and was hoping and betting that eventually her natural curiosity would lead her to try more new experiences. Today she is almost nine years old and has absolutely no trouble separating from me for parties, overnights, etc. This morning she was just telling me about a week-long girl scouting camping trip she wants to go on this summer.
So here is how I think this relates to what you said about your T.
quote:I, on the other hand, always want her to be the same, and very predictable.
Any parenting book these days will say that consistency is HUGE in establishing security in their children. And although I know your T isn't your parent, the therapeutic relationship often mirrors that of the parent-child relationship. Which is why a T must be consistent with their boundaries. I don't see anything wrong with what you are wanting, Cipher.
quote:she expects me to exercise trust in her when she doesn't answer, that its nothing personal, because I need to practice hanging on to the connection between us.
I am just really confounded by this. How does one "practice hanging on to the connection" when that connection has never been reliably established in the first place? IMO, her "rules" are too unpredictable to really be anything reliable. This just sounds to me like parents who want to force their kids into "trusting" before they've taken the time to build up enough experiences to establish that trust.
And I also want to be clear, that I'm not saying that your T must necessarily answer every text immediately. She may even establish her boundary at no texting, ever. But I really hear you saying that you need her to be predictable, and always the same. What that specifically means is up to her. But IMO she is evading her own responsibility to establish consistent boundaries by expecting you to "trust" her when she is inconsistent. But to me that is a contradiction in terms. How can I "trust" someone who is "inconsistent"? My daughter learned to trust in our relationship by my being consistent. I just really think you might need the same thing.
And now I will get down off my soapbox.
Hugs,
SG