You should check it out at HLorenzo, they're getting a size 3-5 iirc. Actually all the Attachment/KKA pieces they're getting starts at size 3.
You'd probably be a size 4 jet. I think attachment is pretty consistent and my size 5 is a little bit too big especially in torso, arms, acceptable in shoulders and fine at the chest... unless I layer but my size 4 is dead on to slightly too tight when I'm uber fat.
4 fits pretty good in the arm. Perfect length for my arms too. 5 is a bit too long and billowy in the arms. Might be good for you I think your arms are bigger/probably longer since I'm 5'7.5 ;p