Sorry you last session was so hard
I hate those kinds of sessions.
I have no idea how to get to a place of attunement in my work with T - sometimes it's there, sometimes it's not. She can be off or I (usually) can. I don't think it happens accidentally I know my T tries to get us there if she notices it I can feel her keep us there. If I let her in, it happens more - usually she is waiting there ready and willing to try. We've also... because I've gone sooo slowww in trusting her I think sort of settled in to a pattern so it's hard for either of us to move out of that but she follows me lead.
Anyway... sometimes it does feel like random chance and I can promise you after an extraordinary session there is almost always a misfire session after. About 18 months ago my T said we were finally getting to the point we could get on a roll for more than 2-3 sessions in a row without me rejecting or antagonizing her. Now it's much more, but we have to keep up 2x/week sessions to make sure the positivity stays there... a week in-between and things just get too distant.
Best of luck to you, it will come.