I used a fabric calculator and entered the stitch count for 7 count fabric. The design size by itself is 33" x 23", which means your fabric would be too small, I'm afraid. :( Plus, I've never made a chest seat cover so I don't know how much extra fabric you'd need to completely finish your project. Perhaps other stitchers on this chat could help you what that part, but like I said, for the design itself, you will definitely need more fabric.

And I just realized I might have misinterpreted what you said. haha! If you're trying to make a seat cover with the dimensions you included in your post, then the 32" x 23" design will be comparable to what you're doing. But if your fabric is 22" x 46" then, yes, you will need more fabric.

Also, take a lot of strands of floss per stitch.