my son had OT from 2 until now. He was very delayed in motor skills (walking, talking, pincher grasp, etc.) Most of his OT was focused on sensory issues (playing with playdough, learning brush techniques, wrapping him in blankets, etc.) It helped with balance and fine motor stuff. To him he felt like this lady came just to play with him with special toys and activities once and week and he LOVED it. He is in it now and doesn't like OT as much because the school OT makes him do "not as fun" stuff like pencil holding, etc.
Are you in the states? If so, most states have a program (in Virginia its called "childfind") but your pediatrician can tell you what its called in your state. Where they can screen him for OT needs and then he falls under the state program until around 4 years old when he reaches under the school system's umbrella. They can formally test and see what his needs are if you are concerned.
HTH