You are correct. If you take 3/4" off of the sides of some, it will make your outer blocks too small.
It also probably means that you will have diffilculty lin ing up your seams with the rest of the blocks.
I would probably change the pattern design if they are all this way. Sash them and then square them up, the difference won't be as noticeable then.
An accurate 1/4" seam is very important, measure as you go and you can catch discrepancies earlier on :wink: