converting guage from 4st/inch to 4.5st/inch

[JessicaSant]

I'm knitting a nursing sweater from Natural Knits for Babies and Moms.

It calls for a yarn that is about 4 stitches per inch on size 8 needles (16 sts and 22 rows = 4").
The yarn that I have is about 4.5 stitches per inch on size 8 needles (16 sts and 22 rows = 3.5") - Here is my yarn and the swatch I made.

I don't want to increase my needle guage - I think it will make the fabric too holey. I was thinking I could knit the large instead of the medium and get the measurements I need?

So.... I tried to do some math to figure this out -- If you can go over this and confirm that I'm going to knit the right size -- that'd be MUCH appreciated.



I have a 38" bust. But I'm 4 months pregnant... my guess is I'll be bigger once I deliver and start nursing (and, this being a nursing sweater, that's when I'll be wearing it). The bust size for a large, using my newly calculated guage would fit 38-40" bust. The finished size will be 44" -- which seems kinda big... but I guess you want a loose-ish sweater?

What do you think?