The typical Thoroughbred ranges between 15.2 to 17.0 hands
(62 to 68 inches, 157 to 173 cm) high, averaging 16 hands
(64 inches, 163 cm). That withstanding....you still sometimes will get a short horse no matter what the breeding. Since your horse is a rescue, he might not have gotten enough nutrition to grow to his full potential. He is only 2, so he might still grow some more.