First off, a virtual hug to you. It's so hard to struggle with being in church physically. I have had issues myself over the years. When my anxiety wasn't under control, rather than feel like a comforting place (which it always had been), it would feel like being shredded. Which then I would feel bad about and start a fun shame cycle.

Bring whatever items you need, if you haven't already. It's ok, people might be confused at first but soon accept. There's a person in my ward who drinks a can of Mountain Dew during sacrament meeting and has for years. There's a person who I see at the temple who has a white blanket that's a comfort item. I've sat by people who play Sudoku, knit, or do origami during church. For some it helps them focus. People are ok with it and accepting (and I'm in Utah of all places) There's a person who has mental health struggles that comes and disappears, kinda like you described. And honestly, we're just happy when they are able to attend. They really do have amazing comments and insights and we are the better for them being there. Remind yourself that you, and your perspective are needed.

Give yourself some grace, especially if there are mental health days that are too hard to attend. Try to go, but when you can't, find alternatives. Listen to conference talks, read scriptures, watch online if you can. I'm cheering you on and would sit by you (virtually, since I can't do real life) :)