Open bite and tongue thrust

I had DJS for severe underbite and open bite when I was 18 (now 30). I relapsed (just the open bite) due to a tongue thrust and I did speech therapy to try to fix it before I got my braces off. I don’t think I took it seriously enough at the time and also stopped wearing my retainer after a year😓. When I stopped wearing it, it really opened up.

I want to try it again when I am able to financially, with spikes to train my tongue. Can anyone tell me how the tongue stays on the roof without slipping forward. When I do it, it’s so slippy and it feels slightly chokey and uncomfortable. What about when you’re sleeping or smiling, is it still always on the roof of the mouth? I also wonder if tongue size has anything to do with it. I noticed my tongue has always been puffy, and I’m pretty sure I’ve had SIBO all my life, which can cause that.

And I’m curious if this has also happened to anyone else. Honestly, the relapse is nothing compared to what I had before, but it has been making me self-conscious, and I have a slight lisp.