Sorry to hear the whole ordeal is getting you down.
I take it from your post that the DWP have not made any application to appeal to the Upper Tribunal as yet? and are still just considering whether to do so? If so then finders crossed they won't take it any further and will just pay you your backpay.
For the record the backpay when it comes, should cover all the gaps from the date of the decision to present.
Best of luck and keep us posted.