I hope you get your quilt done for the party. Years ago my mother took a quilting class and decided to make a king, which of course is twice the work of a twin and she didn't have all the quilting done for the last class, but nobody cared. I know in your case it's a bit different.
I have more than one project going at a time as well. My trouble is I hit the wall on what I know, and if I do a bit of reasearch or watch a couple more quilting shows the answers come to me. Perhaps in your case you could talk to someone about the troubles you've been having. At least a good part of the time there is an "easier trick". Half square triangles being the prefect example. I thought having two sqaures and sewing them together to cut them apart was the best answer, but then on Egg Money Quilts she sewed eight at once and then cut them apart! Talk about easier!
Best of luck to you.