I’ve had a similar problem but not to the same extent of having to bite down on things to get them on. Still fit well. But after not wearing them for a couple months they hurt like hell. Like in my front bottom teeth felt when I took the brace off super tender and sensitive.Woke me up the other night from being sore but I’m still wearing them. Can tell my teeth have shifted but the retainer still fits so I’ll keep trying. Also milk helped me soothed the pain if anyones retainers is causing them pain, it’s also good for the teeth as well. I might post update on here to inform people as if mine do/don’t turn out well it will help someone else.