Going to look at a horse tomorrow (first time buyer)!?

[O.o]

how do you know if this horse is for you?
you trust your gut.
either you "feel" it or you don't.

that said, I'd be VERY suspicious of anyone who claims that an ex-race horse that's that young is so perfect all around......that's not common.

Here's a few things to keep in mind:

1. the horse should not be ready (saddled and tied up, ready for you) when you get there.
if she is, the seller may be hiding something

2. you want to watch the horse being caught, groomed, tacked up and ridden by the seller.
if the seller insists you do it all, be suspicious. the seller might be scared of the horse

3. if the horse looks already ridden before you show up (has sweat marks, etc), be suspicious. why did the seller have to ride before you showed up? if the horse has to be lunged before ridden, this isn't a good sign either.

4. the seller always rides the horse first. no exceptions.
the horse should be great in the arena and outside of it.
watch the steering, stopping, transitions in speed.

does the seller look nervous? hold a tight rein? slack rein?

what kind of bit is being used? twisted? is there a tie down?
does the horse look calm, relaxed? does the horse react or respond?

If the horse is so great, she should be ridden with a plain snaffle bit (smooth no twist, no shanks)

Above all:
Trust Your Gut

once you get all of that squared away, then worry about the height. that's not important compared to the temperament and training and soundness.