I'm working on an overshot pattern and very frustrated. The pattern is the placemats from Overshot is Hot (pg 42). I'm using the exact threads called for in the pattern, 10/2 pearl cotton for the warp and tabby weft and 3/2 p.c. for the pattern weft. As you can see from the picture, my pattern threads are too far apart, not snuggled up to each other like I think they are supposed to be (and as they are in the picture in the book). In fact, I even cut down the number of threads in each horizontal section from 6 to 4 but the whole thing is still way too elongated. The section I've pictured should be square. I'm beating as hard as I can but the pattern threads are still too far apart.
Of note, I also did the overshot bookmarks from this same book and they came out fine, though they used 20/2 and 10/2. Any ideas on what I'm doing wrong? Thanks in advance.