RE: Pic on me and new/used bow....
Well, except for the fact you've got HAIR, you look darned near like a smaller version of ME! You have my sympathies.<img src=icon_smile_big.gif border=0 align=middle>
Definite agreement on both the grip and draw length. Try curling the middle, ring and pinky fingers between your palm and the handle, and loosely wrap your forefinger around the front of the grip to lightly touch your thumb, just enough tension to keep the bow from flying across the yard. Also, you want the handle to ride on the thumbside of the line running down your palm, starting between your thumb/forefinger down to the middle of your wrist. You've got it right in the middle of your palm like you're toting a suitcase.
Your basic stance is okay but needs a little fine tuning. Head comfortably erect. Bow arm shoulder held in a low, relaxed position. Elbow not locked out. However, you are leaning back slightly at the hips. The angle of your arms is making you look whompy-jawed. Rather than aiming with your arms, you need to establish a solid 'T' with your bow arm and string arm elbow, then bend at the waist to get on target. For the target you're shooting at, you should be bending slightly forward rather than slightly back. Like Matt says, that could make the bow's draw length look even shorter than it actually is.
If you can't get the draw on that bow lengthened, then have the shop tie on an extra long string loop for you to shoot with. I've shot bows up to 2" shorter than my actual draw length pretty well with that little trick. Not an ideal setup, but it will tide you over until you decide to break out the checkbook for another bow. It WILL happen. Sooner or later...<img src=icon_smile_big.gif border=0 align=middle>