New colors and fighting with knits

Before I got addicted to buying fabric I was addicted to buying paints.  Watercolor paints, specifically, and mostly from the Daniel Smith website, which once upon a time had the nice feature of listing their well-photographed colors in order of color rather than alphabetically, and letting you select and arrange color swatches before you bought them (sound familiar?).  After a while I found myself converging to a basic palette of about 16-18 colors.  And when I switched to oils a couple years ago I kept more-or-less the same set of pigments:

As you can see my palette is heavy on the earth tones and primaries.  Not a whole lot of really bright colors and very few secondaries (orange, green , purple).  I find I can mix most of the colors I want from here, but lately I’ve been running into a few that are hard to get to.  Specifically, stoplights, which appear in all of my city scenes, and whose greens and reds form the “jewelry” in a lot of recent paintings.  So Sunday I went down to the art supply store and picked up these:

I’m kind of looking forward to playing with some new colors.  I also picked up some damar varnish, which I thought I would try using to mix a glazing medium.  I usually just use linseed oil and OMS (a more refined turpentine) to make my mediums, but I always find that my glazing mediums break up when I try to lay them over another layer of paint.

In case you think that all I do these days is buy stuff for projects without using them, here’s my progress so far on the burda maternity wrap dress (a hybrid of envelope pattern 5456 and magazine pattern 06-2010-132):

Overall I think this is going to be a great dress but sewing this stretchy jersey knit is driving me crazy!  I feel like I must be missing the appropriate tools.  I have a stretch needle and a twin needle, but the fabric keeps bunching up as it is squeezed under the presser foot.  The center back seam is all bunchy (after 3 attempts to sew it properly.  The neckline kept pulling in as I was trying to topstitch it:

And the hem of the wrap part got all stretched out:

Then of course there’s the problem of the fabric stretching out under its own weight.  Having run into this problem before, I made up the bodice and skirt sections separately and pinned them together to see how it stretched.  It was pretty ugly— the back bodice stretched by about two inches!  I tried two things to fix this— taking about and inch out at the horizontal seams, and pinning elastic into the waistline seam so the skirt could rest a little on my belly and not all hang from the shoulders of the dress.  Both helped, but the bottoms of the armseyes still look all distended.  Ugh.

I’m wondering if getting a walking foot will help with the fabric bunching since it seems that the main problem with bunching is too much pressure from the presser foot (I don’t think the pressure can be adjusted on my machine).  I was also thinking of getting some fusible bias tape because I keep reading about this stuff on sewing forums and blogs and it seems that lots of people swear by it (can you also use this stuff on seams that are intended to stay stretchy?).  But any advice you can offer would be really appreciated.  I do like this pattern and plan to make this dress again, at least in a non-maternity version.