How much taller can human growth hormone make you?

It depends: There are fda approved indications for growth hormone use which have been well-studied. Depending on what age/stage of puberty hgh is started, and for what indication, growth expectations vary.

@ your age=none: Growth requires open growth centers in the bones. These generally close in men by 18-20 or women sooner. Once they close growth hormone does not make them open or the person grow taller. If a kid of 9 has bone maturity of a 6 yo & a deficiency of HGH, treatment may allow him to reach a normal height. A kid with a bone maturity of 17 given HGH would maybe grow a little, but not much.