Might be alright, ask your brother or just try to follow what he did, ask him and your grandpa when their last growth spurts were. If you want to try and force one you can use hgh, but fasted cardio and training legs more often will probably help
My brother was a late bloomer and he never did something to improve his looks or his height he just existed. I actually have much better genetics than him so I think I'll reach his height or probably become even taller (already training legs).