I have never done any monogram work so, forgive me, aspects of what you've tried hard to explain has gone over my head, however, I assume you are aiming for a square so it will correspond with a graph..is that right? Then of course you want the rounded edges. However, is it worth considering a technique like you see with the lettering on this page? This seems to create lettering and yet it's dependent on the letter shape more than a graph as such. Take a lot anyway and see if it helps. You have a nice idea there.