I purchased a Toyo tap wheel thick glass cutter and a Leponitt heavy duty running pliers and (holding my breath) I cut the glass down to a smaller size (where I had drawn the lines on the original picture). It worked! Of course, I have to so some coldworking on the edges now, but I have my plate, albeit in a smaller version!
Again, being a newbie, I would love to hear any suggestions on how to use the cut off pieces.
Just wanted to share with the forum what I did to solve this issue. As a person new to glass, I was at a loss, but I did a lot of research online and came up with a solution that worked!