Second, forget about appeal. This attorney just wants to earn you more money. I do not want to discredit your attorney, but he already did his best and can not be any further help and will be worthless at this point. Go to find another good attorney and File NIW again.
Here is my story in short.
I have Ph.D. in engineering and 9 journals and 27 citations, postdoc research in hot area at top university at the time I filed NIW. I got 8 good recommendation letters including one from government research lab. I understand my case was not strong at the time of filing. But thought I will get good luck too because many other succeeded and easily get green card by this NIW. Unfortunately, I became one of miserable guys.
I hired an chinese (Taiwaness) attorney in Houston. This is an one-person law firm practising all law areas, now I can understand how poor service he can provide. Only advantage is he charges you at relatively low attorney fee. "It was absolutely my biggest mistake ever made
'小便宜吃大虧. Everytime meeting with him, his only word “no problem, no problem”. He did very few wording on recommendation letters. He wrote a very very long statement (up to 80 pages, as a matter of fact, 90% by copying/pasting my recommendations repeatly over and over again in different sessions) within one week ( I feel he might just spended a couple of hours to copy/paste other documents. I was so upset and feel his statement is so poor. He still smiled to you “ no problem, no problem, it worked for others". He claimed he did every case in similar way and 95% succeeded (good luck for most customers he had, who knows). But unfortunately, I fall into that 5% groups with back luck, really really bad luck.
I have got to work now and will continue my story if people feel interested.