All horses and ponies look taller than they really are when you're standing next to them. My mare is exactly 16 hh . . . I have to stand uphill to mount from the ground if I don't want to lower my stirrup. That, or lead her into a ditch (there's never a bucket or a stump around when you need one).
I have to find a way to get uphill on Bay too.... especially since I loosened my cinch up ;~D