I can feel your pain! I've been there. I too did the things you have done, starch heavily tape down to the floor, add batt, then starched top, pin with safety pins (1inch so little) no more than a palms width. I've used walking feet, freemotion, etc. I've made more quilts on my old mechanical machine, but I have made better ones on my computer machine. I don't think I have any of the puckers since getting my computer machine. I also found I did MUCH better working on the dining room table. The extra space behind my machine and to the side, made quilting a king size very do able. This last quilt I had lots of issues with tension, but that was I think due to a thinner bottom thread (bottom line, and embroidery bobbin thread).
There have been lots of suggestions here, I think I would try and get at least a nights sleep before you tackle it again. I've found that my frustration level causes me to make mistakes, and sometimes sleeping on it helps to figure out something new. Good luck!