Becky,
Beautiful quilt! Thanks for the information about your machine, etc. I'm glad to hear you say something nice about the budget priced machines. I sold a lot of those less expensive Singers for two years. While I currently have two top of the line Vikings, I also have two featherweights, and two singers from the 60's. I sewed a lot of clothes, costumes, and home decor on those Singers before buying my first Viking because I wanted to do embroidery. As long as you don't abuse it your Singer from Walmart will be fine for a few more years of quilting.
Also, please do not apologise for stitch in the ditch quilting. Celebrate the design of the piecework.