Guy, 6'7 is VERYYYYYYYYY TALL. I know there is 50 % of the internet who is reaching that height, but outside I'm far from that conclusion. I was checking a bit Celebheights and in only one page I saw about 3-4 guys pretending they were about 6'8 / 6'10 (Kevin Durant page).
If you reach 6'2 (I advice you to do not think of two operations at the moment), then you will be tall. 6'2 is tall, nobody can say it's wrong. I know that on internet it's about average, but internet is internet and people are of course upgrading themself.
Also, don't go over 16 cm
173 + 16 would make you 189, 15 would put you at 188 so a legit 6'2. It's perfect !
As I saw you're only 18 you could reach 176 or maybe 177 ! maybe even more you will be easily 175. So 175 + 15 would put you at 6'3. The height of James Harden (dont listen that crazy 6'6 listening, that's absolutely not the case)