As said above... you'll be suprised how much he changes still! IMO he's still got a baby face and an immature frame... my boy was the same and hasn't REALLY looked like an adult horse til this year and he's 6 in October!
Nope, nowhere near finished and furnished yet I'm afraid You will have a bigger boy on your hands! Previous warmblood baby was very similar - he went through every stage of gangly and never filled out body wise till he was 6 properly. Now, 8, he's standing 17.3hh almost and was 16.2hh as a 4 year old....
He looks a lovely boy. He could still go up a bit yet as he is only just coming up 4. He will look great next year when his muscle starts coming on aswell, they alter so much between 4 and 5 yrs.
He's a BWB so 3/4 TB and 1/4 Trakh. By Groomsbridge May out of a Fleetwater Opposition mare. Mum and Dad are both 15.2 ish . He's being very quietly ridden away just now so slowly starting to develop muscle.
My full trak is coming up 4 - still very gangly and I feel will take another few years to really fill out. He's standing 17.2 at the moment - I'm expecting him to grow a bit more :/
erm... sorry to rain on your parade but if you think he's stopped growing at 3 you're in for a shock! By boy has shot up loads since he turned 3... and still hasn't stopped at 17.2hh!