how to bind off so it's really really stretchy????

[VictoiseC]

Hi all! I've finally finished my Interweave shrug! (thanks to Ingrid)

Thing is, I know shrugs are supposed to be tightish, sort of, around the arms. I used this yarn that really breaks easy (which I willnever ever use again) so I did try to bind off loosely but I still feel like
if I stretch it too much when I wear it the bind off might break.

(This yarn broke several times just while knitting)

I'm thinking of ripping out the bind off (if I can) and trying a looser bind off. I think I read about something in EZimmerman's book but I can't find my book. Any suggestions ?