Finished Object: Hey Teach!

Pattern: Hey Teach!
Source: Helene Rush, Knitty (Summer 2008)
Yarn: Valley Yarns Goshen, Navy
Needle: US 9

Well, it's done. I'm not thrilled with it, but I think it's fixable. Let's start with the things I like about it:

• the pattern was so fast to make - a whole cardigan in only 5 weeks!
• the yarn is incredibly soft, but has beautiful stitch definition
• the lace is perfect - not too frippy, but still feminine
• the color; yum!

So here are the things I don't like about it:

• it is way too big.  I used a US 9 instead of the US 8 in the pattern, so I probably should have gone down a size.  I have lost all my baby weight, but you can't tell when I'm wearing this sweater!
  
• the buttons I used are too heavy for the yarn, so the button band side sags down.  I wore it to work yesterday and was tugging and adjusting all day.

I think that if I sew some matching twill tape into the button band, that should fix the sag.  As for it being too big, I'm considering taking it in.  I found this article, and might try to take it in at the side seams.  I don't have a serger, so I'm a little scared.

Thoughts?