Need help, shooting low and right

[Full Metal Jacket]

Topic says it all...at 10 yards with a .45acp 1911 5" I have fairly good groups. Problem is i'm aiming at the center X, not the Southeast area of the Silouhette. Also, after about 30 rounds my hands get shaky, which affects my aim greatly. I think its because I extend my arms out too far, putting unnecessary strain on them.
what do y'all think?

 

[Slateman]

According to the chart, you're tightening your grip. Also could be limp-wristing