I think there's too much tension on the tubing of your peepsight, it looks like it's pulling on the string. And you need to change your handposition on the bow, no fingers sticking out. Try to rotate your hand with your elbow sticking out horizontally, in this little youtube movie, you'll have to watch untill 2.54min, the chubby guy has a perfect grip in my opinon.
http://www.youtube.com/watch?v=DIXZi2JXEW8

hope this helps,

Frank
Belgium