I-134 for Fiance-I Have cancer & on SSI & earned too little $-can Immigration make medical exception?

I requested a medical expedite and received a US side approval--but now my fiance must apply in Pakistan. We were told in writing by Immigration to fill out an I-134 form. But I didn't know until today about the minimum $, which I am about $1,000 short of reaching (My SSI was $17,000 for family of 3). Will my medical excuse--Cancer & 4 surgeries in 4 months enable me to be excused from the $1,000 monetary shortage? Will the fact that I'm on SSI be held against me? What should I do? I have some cash but it's in a safe deposit box and not in a provable bank account or etts form (due to previous fear of bank collapses) and it is too little anyway.