Nancy, I don't think you are a terrible teacher...I just finished reading r-ds of my kids autobios and I was/am as disappointed as you. Many didn't even bother to turn theirs in, and the finals are due next Friday.
I wish I had a solution for you...I even sent home long letters with due dates, NO LATE WORK, etc., and while it helped with some, apparently not all.
I see that I have to offer some specific lessons on Monday and Tuesday, so those that did turn them in can fix some glaring problems...but I think that is always the case. It is projects like this that reveal areas that need to be retaught....
I had to issue 14 hard earned F's for this progress period, and all 14 students are now in the afterschool Academic Opportunities Program. Actually, not 14 students, since some of them earned double Fs since I teach in a block.
I don't think your expectations are too high, never think that.