Half the kids I see at top level mounted gains seem too tall for their horses, but the horses and riders are always skinny and athletic and look fine for the sport. I think you'll look just right on a 14.2, assuming your weight is ok too.
Makes it a lot easier to vault on. My friend's eldest granddaughter is on the local PC team and she is 12 and tall and skinny on a 12.2 and am so jealous as she hops on the pony as it is cantering.