Your main problem is that the VA can do what they call staged ratings. You need evidence that your rating should have been higher, back then. If there was any mention of unemployability, in your claims file or medical records, previously, it would be the evidence you need and the more it's mentioned the better. Personally, due to the retro, I would pursue it. Nothing ventured, nothing gained.
I was originally awarded 30% for PTSD and I thought, great! Within the one yr appeal period I realized I was much worse, so I appealed. It took 10 yrs, with periodic increases, for me to win, but I won, 100% retro, to day one of my claim and when I started I knew nothing about the VA, their claims system or PTSD. I had zero evidence when I started. I now feel I am somewhat an expert, if only for my claim. jmo
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