One side of Cardigan is longer than the other

[NBknitter]

Hello. I am almost done with a simple cardigan for my DD. The pattern is haiku from knitty.com. It is a sideways knit cardigan so the edges of the 2 cardigan openings are the cast-on and bound-off edges. Well, my cast-on edge is much looser than the bound off edge and so that side of the cardigan is longer than the right and looks sloppy.
How can I fix this? Thanks for any advice. BTW, I used the crochet cast-on method.