Can’t find a boot size that fits.

I recently bought the Ride Lasso’s in a 8.5 and 9. When i rode with the 8.5 on my toes go completely numb and i can’t stand the cramping, but the 9’s i can feel some heel slippage. I honestly have no clue what to do because I don’t have the funds to be going around buying boots so I’m kind of stuck here.