Can I get a doctors opinion?

I'm 15 and I'm 6'5, how tall do you think I will get?

I had a mini growth spurt between 11 and 13. my dad is 6ft and his family is tall, my mom is 5'6 and her family is average. my dad says I'll get my last growth spurt anytime between 16 and 19. I really wanna get past 6'8. at least 6'7. I'm 295lbs and I have some back issues which is why I'm certain I would be 6'6 right now, another question: if I get down to 220lbs (I'm gettin a personal trainer this week) will I get that inch back? I feel like I get weighed down a lot. I wake up at 6'5 but by noon I'm at 6'4 and 6'3 end of the day. One of my best friends is 16 and 6'4 and 165lbs and he stays 6'4 most of the day but eventually makes it down to 6'3.

Anyway, if I fix my back up and everything is fine, how tall will I get?