Hopefully, my experience could

help you somewhat. I got same thing last summer. my OPT was denied becasue they said I hadn't got 9 month F-1 status when I applied. They were totally wrong! my ISO helped me do " open to reconsideration" I think your ISO should know how to do that.

Now, I think the only concern is that you are out of the grace period. I graduated at June, and got denied letter on July, I was still in my grace period. that's the only differnce.

It's a big issue, so my suggestion is go to a lawyer. if you still have some grace time, file open to reconsidation and H-4 applicaiton quickly. That's what I did.
I simply withdrawed the H-4 application after I got OPT approved. so take it easy, thing may not be that bad