Sasumu, I think most of us can totally emphasis with your frustration at getting gendered by your brother. It's always annoying to get stereotyped for something that you're not.
As an aside, it sucks for ftms, but growth velocity pretty much drops to zero by about 14-15 years, with peak skeletal growth around 12 years of age. I'm quoting the average time line here for what they call phase III skeletal growth (taken off hand wrist x-rays and cervical x-rays). In other words, there's a huge advantage for early intervention for ftms in that there's a higher chance that you'll grow to the cis-male height that your genes would allow. I'm not an expert on this (my interest in skeletal growth lies elsewhere) - but I suspect that mid-teen hGH and T would probably allow for some additional growth in high for a mid-teens ftm.
And I agree with everyone else. Shaving is so over-rated - I hate it with a passion (especially since I used to get a lot of acne around areas where I shaved).