Stuck in sleeveville

I've placed yet another order for more yarn for this sweater. I'm almost done with the sleeve, but I'm MORE almost out of yarn. I should have ordered 3 skeins last time, instead of two. I blame this on latent chemo brain, but it could just be plain old fashioned poor judgement. I'll grant you that the first sleeve took two skeins of yarn, I swear.

So, what's wrong with this sweater that it eats yarn? This is always a scarey question. The sweater IS turning out bigger than I expected. I did check my gauge when I began, but it's entirely possible (likely, given the yarn problems I'm having) that my gauge has relaxed as I knit. In addition, one of the balls in this last batch of yarn had several knots -- when the ball of yarn only has 56 meters to begin with, this makes a difference. As you can see, I'm ALMOST done with the sleeve.

So, the yarn for Karis is out of the box. The Rowan book is on the dining room table. The charts sent by Sharon Miller from Heirloom knitting are being perused. I'm about to try Kidsilk Haze - and given what I've heard about the pleasures of this yarn, I feel like I'm about to try an illicit substance.