I suppose meh means different things to different people the same as feeling ok differs from person to person.
when I say meh it means 'don't ask' either because I can't explain or because there is too much for me to explain and my brain can't put it in a way you will understand before you get bored!
I feel ok when things are on a level e.g. I am not over tired, able to get up, dressed and out before 3pm when my mind is not full of stuff fighting for my attention and I do not have reflux! I am in pain 24/7, can't sit up unsupported or walk and struggle to pick up a cup without spilling the contents, so to others I am not ok, but to me this is my 'normal life' so if ever these things were not there I would be far more than ok I'd be fantastic, ecstatic!