I agree that it's not about succeeding or failing at attachment. From what I understand, people tend to end up with their specific attachment style from childhood. Mine is definitely anxious/preoccupied. No matter how much therapy I get, I doubt I'll ever have a 100% secure attachment to anyone. It's just the way I'm wired. I can (and have) become more aware of that issue and understand it better. So that I can realize that when I wonder about someone abandoning me, it's probably coming more from me and my fears/self-doubt than from the other person.

I don't think your T is trying to push you away at all. You were saying you weren't happy with her style, so I think she was just trying to say that if it's not working for you, then you can do what's best for you. Not that she's going to leave you. But that if you realize it's not working with her, that you could in theory choose to leave her. That she would understand.