that horse is fine, get him in shape and ride snot out of him, I rode a 16 hand walker for awhile my GF said I looked great on her, I'm taller but I'm 220lbs and bet Im not that far off you in weight. While you may "look" a bit outa sorts, that horse doesnt care. Not to mention, your weight is lower than mine, bet that makes a big difference to the horse. I would say you might need a bigger saddle, :) but you know who cares go have fun be happy love thyself.
"Ride the snot out of him", really?! That horse needs groceries, he is in poor condition, is fine boned, and is trying but doesn't look sure of what is on his back, look at his expression and ears. Joe4d, a good horse person would first look at the horse and have it's health and well being in mind, instead of themselves..with no top line, lacking muscle tone, no, a bigger saddle won't help, it is only going to sore the poor thing, and may even go so far as to say it could cause you even MORE problems down the road. So no, this dear horse IS NOT for you.
There is nothing wrong with being heavier, we all have some extra poundage to loose, but come on. It is about time we become honest with ourselves AND the horse were going to be riding and/or buying. Horses are very stoic animals, often times it is up to us riders to see and know the subtle hints of uncertainty and issues before the horse shouts it out by dumping us on the ground, wringing it's tail, wrinkling their nose, and bouncing around or other not so subtle clues.