I had some dental work done that messed up my jaw. He took the bite of my back teeth out of occlusion and caused my mid-line to shift a couple millimeters.
Do you think yours could be caused by dental work?
I ended up having to go to a TMD clinic for a year. They made me a special splint--it was bulky but made my jaw relax. Those otc night guards are not comfortable, not even the boil and shrink ones, if that's what you're using. I tried that before going to the clinic.
I did find a very thin over-the-teeth retainer on ebay that helps some too. It's like the ones here: https://www.ebay.com/sch/i.html?_from=R40&_trksid=p2380057.m570.l1313&_nkw=custom+retainer&_sacat=0
I see they also have thicker ones now: https://www.ebay.com/itm/123182027085?_trkparms=ispr=1&hash=item1cae38914d:g:XMUAAOSwlAdfofuM&amdata=enc:AQAGAAAA8BgaEd/PkAls+pyyjE3wKt8IlyhYsJoFXNr6tJV5T15OghqdJaFedTMcZQdpcUURFoLw13ZX9w7t9o9XOL0HYB6pEwpUIpe6hcBoeG/Dz8HSYonzZEaghgUXIDFXGthPtSbLI2wtxwxJdNeQTjqTvbxNizmAX0GJOliVL5P6MQR/P41SI/tWohPZlLz6K+ut6b2Mx1+b4EEsJojzlvlvr0rjqw3oGqdjvDaI36wmn9NymbRFqempdLEz5hmi+97idbsWBrsjWknNwYNf/h/eultWjwiTvM/SHf//H84YVGuSQwJ0v9pCjkYny0oIZrB6FQ==|tkp:BFBM2LyT-rZf
If I needed to do that again, I would consider getting the thicker ones instead. They're expensive but not like the splint was.
Also when I ordered from eBay, I requested a lower one but I would get an upper next time because the lower is hard to use. My back upper teeth hit it in a painful way.
Also these eBay retainers are very tight to the teeth and that can get uncomfortable at times and they're pretty thin so not sure if you would grind through them after a while. I don't grind; my jaws just are not aligned well so they hurt.
However, sometimes just that little extra spacing can help relax the jaw enough that maybe you wouldn't grind as much.
One more thought is check with your regular dentist.
Later, the same dentist that referred me to the TMD clinic said he could make me a splint and that it might be covered by my health insurance. It wasn't so I didn't have him make it even though it would have been a lot less expensive than the TMD clinic version. Just something to look into maybe.
Some insurances are covering TMD treatment and a dentist's splint probably would be the best. It is for me.
Anyway, hope you can figure something to help.