2 1/4" folded in 1/2= 1 1/8 you are actually sewing with. If you use 1/4" seam, you are talking 1/2" on the front and 1/2" on the back, then you still have 1/8" left over which depending on the thickness of your batting. I don't like puffy batting so I use Warm and White or 80/20.
If you use a slightly larger seam then the math will work. Or you can cut your binding 2".
JMHO