I would call that quite petite. I'm 5'7" and about a size 10 with narrow shoulders and waist (post pregnancy I have gone from skinny to voluptuous which is rather entertaining, my hips sway and my boobs jiggle when I walk which is a novel experience... anyway... I digress).

I find a Bubba Moe or similar difficult to wear comfortably. Is there somewhere where you can try one? How do you find the Ergo? If you find it comfortable then possibly the Bubba Moe will work for you - Ergo doesn't work well on me because I have narrow, angled shoulders; the strap angle was too wide.

Otherwise, a ring sling might be worth considering.