Grid Rules

I am 51, I was 49 when I applied for SSDI. The last 15 years I have worked as a sales associate, sewing machine operator, and in a factory as an assembler. I am wondering if the grid rules will apply and help my case. My physical ailment is I have a rare disease in both my feet (I have had surgery on the left foot twice and once on my right foot) I also have plantar fasciitis in both feet and I cannot walk or stand very long at all without having to sit. I also use my bum left foot to work the pedal on a sewing machine so I cannot do that job any more.
the disease I have in my feet I also have in my hands but it's not all that bad in my hands. I also suffer from some mental issues too.
I am just wondering if I will fall in the grid rules for SSDI.

Lisa