Try spliting the pills in half and see what happens. (it's hard with the sublinguals but possible... use a sharp knife)
I can normally get longer use if I spread it out, but I am pretty constantly nauseous, but I don't vomit, so I consider that a win.
Phenergan and compozine knock me out, so i live on the zofran. They will only give me 12 pills at a time, and I am paying 15 each refill, so yeah, they are gold, but SO worth it. I misplaced my last 2 the other day and was in HG hell again for about 48 hours until I could get more from the pharmacy.