ruby2shoes

For the first time ever I am considering throwing out a quilt. My intentions with my 78" x 78" Jacobs Ladder quilt was to quilt it in a diagonal grid all over. I am only about 1/3 of the way doing my first direction diagonals and I am having serious thoughts about continuing. I am getting quite a lot of "pull and poof" in the fabric between my stitching lines and frankly, it's looking ghastly and there is no way I can even contemplate pulling out all my stitching, re-basting and starting all over. I initially tried doing vertical columns but they too ended up with "sagging".
I was so careful with my pin basting....over 600 safety pins and 2 split fingers says I'm a little hero in that department! I have my quilt well supported with tables behind and to the left of my machine which is sunken flush into the table and I am mindful not to sew too fast with the walking foot.
(1)Is this worth persisting with or should I just write it off and move on?
(2) Once I do the diagonal stitching in the opposite direction is this likely to straighten out my sags?
(3) Would I be better off to not do diagonal griding but instead just continue with this one direction of stitching and then matchstick the columns?
(4) Do I make the trip to the rubbish bin with it? Apart from a heck of a lot of time invested this quilt was not a particularly expensive investment.....blacks were all made with scraps from my stash ad therein lies the problem perhaps...a lot of different, and possibly inferior quality fabrics have gone into the blocks....? distortion/bias problems.

I'm really looking for some guidance on this one..never had this sort of problem before and don't want to persevere for another week or so if I'm only heading for disappointment. I don't mind a bit of "sag" here and there in my quilts but this is pretty much all over my columns even though the photos don't show it.