You can't look at your own growth path and compare it to your son with expectations. I was 5'7" in LL. My son was 5'0". His growth pattern followed his mother's side of the family. He grew to be 6'2".
His sister was the same. She grew fourteen inches in eighteen months in middle school. Before she grew she looked like a clown peddling a bike down the street. My daughter was an athlete. But we have some good laughs now about when she was a geeky, spastic, bean pole (5'10" 120) with braces.
What was freakier was a five foot, 12yo boy with a deep voice.