What's my chances I'll be 6'+?

I am 15 and 9 months (M) and currently 5'9. My mom is 5'2 and my dad is 6'. My sister is 5'7. My parents grew up rather poor in a third world country so most likely did not have the best nutrition and therefore could have grown more. My paternal grandfather is also 6'. I hit my first growth spurt at around 8th grade (13.5-14) when I went from 5'2 to 5'7.

Somehow, I have only grown 2 inches since then and am scared I won't be taller than my dad, since all of my friends are taller than theirs. My sleep is not the best, since the start of school this year I've been averaging around 6 hours but I am trying to fix that.

I wear size 11 4e shoes since I have big wide feet, and I have a 73-inch wingspan. My hands are also slightly bigger than my dad's. I started to get lots of acne over the summer, but none of my friends have had any yet. Apparently the mid-parental formula says I'll be 5'9 +- 3 inches, but it says my sister would have been 5'4, yet she's 5'7. Does this mean I'll also grow at least 3 inches past my predicted height?

I have had armpit hair since around late July. What can I do to ensure I keep growing? My dad said he grew a lot in his upperclassmen years (11-12th grade), I am just starting 10th grade. Thank you everyone