I just had a thought - did you do the swatch in one color, or in the color pattern? The colorwork is going to make a little tighter gauge than a single color. Also, it wasn't really necessary to do the gauge in the round as everything but the sleeves is knit flat, and even they might be. You might want to do a flat swatch then, knit on RS, purl on WS to see how that affects your gauge.
sue- knitting heretic