I've already tried all of the suggested steps. In a chat with support, it was suggested that restore? my ipad. Not sure if that's the term but think he meant wipe it & reinstall using my icloud backup (which I ended up buying more icloud space). My problem with that is, I'm not sure if my backups are backing up my total ipad and if it isn't what will I lose. The size of the backups don't equal the size that shows in my storage, which is why I'm not sure I have backed it all up. Hope this makes sense.
I think most of my problems started when I couldn't update to 15.0.1 or 15.0.2. I ended up solving the problem by removing the sim tray then it updated fine & I'm now on 15.1.1. That could be just a coincidence but somehow I have my suspicions.