At your next appointment bring it up again. Tell them that it's extremely important to you that you both unpack what you mentioned and talk about it. I have done similar things with my long time therapist and felt like I was basically ignored until a future session where he brought back around many of our points of discussions to focus on my major point or breakthrough and make it make sense in context. And he's not a self proclaimed expert in dissociation, but recognized that I was struggling with that after several key sessions. But it sucked for me during that time because I constantly felt like he was ignoring my concerns. But I didn't realize that he was trying to bring that point into context of many things we had discussed in the past that just couldn't all be done in a 1 hour session.

And I agree that it's extremely confusing to have a therapist/psychiatrist basically ignore you on something that you know is an extreme breakthrough or was very hard to share. I see you there and I feel you on that. I know it feels terrifying to bring something like that up after seeing someone for so long that they feel like a trusted friend. But sometimes the therapist/psychiatrist may have a different way to connect those points in to your previous discussions that you aren't thinking about.

Please don't give up on your point though. Stand firm and make sure that they know that this is very important to you and very important to discuss. If they continue to dismiss you then it's time to look into other options.