I fixed the gaping at the back at my neck with the same adjustment Rae made, except I only took about 1" out.
This one fits pretty well, but is too snug under my arm pits, and a little tight across my bust.
I thought perhaps, rather than making additional adjustments, an FBA or adding darts, I could just try the also widely popular Grainline Tiny Pocket Tank for comparison.
This is Nani Iro san ritsu double gauze. I made a muslin in size 6, and decided to taper the pattern below the bust into a size 4. It worked well, but the finished shirt is a little bit big in the shoulders, and slightly too low cut, so more adjustments are necessary for a perfect tank.
I have been wearing the Grainline one a lot more, but it's not a completely fair comparison because even though I love the print, the voile is a little sheer, and wrinkles quickly, so, poor arm-hole fit aside, I just can't wear it as often as the beautiful Nani Iro. I prefer the hemline and the bigger pocket of the Wiksten so a mash-up might be in my future.
Both are really nice patterns and fun to sew. The Grainline pattern is especially professional. I used french seams on both so they are tidy inside as well.
Thanks for reading!