This is something I'm rather experienced in. I'm about 5'3" and when I started gymnastics i was about 4'9. My problem was not jumping to the high bar, it was jumping to the high bar with the right form in order to do a long hang kip. The secret is to jump to the high bar just like you jump to the low bar from the ground. When I jump to the high bar the right way it feels kinda like I'm pouncing on the bar because if I just lean over then my feet get behind me, but if you jump too much then you have too much power to do the kip afterwards.