I love beckypb's answer - we are all here to help one another. The embroidery definitely needs to happen first. The good news on this pattern is the extra size is often part of the pattern. When you get to the quilting stage you will just pick a pattern that will not go over the embroidery.
The oversized oatmeal strip is cut at 19". Once you have completed the block it will be trimmed down to 18 1/2" x 18 1/2". Check to see if you sewed the oatmeal strip in the correct position at the top of the block. That might make a difference with your final numbers.