How tall can I get in future?

I asked this question recently, but, since I have recently learnt some more information regarding my height, I thought I’d ask again, being more specific. I’m 15 in 2 months-ish. I’m just over 5’8 in height. I weigh about 205lbs, but I’m not hugely fat as such. I have been described as “chubby”, but I’m not really…fat…just…well built? Hard to explain. Anyway, my mum in about 5’4 and my dad is about 5’9, about 1 inch taller than his father. My dad tells me that he used to be really tall for his age, until around my age when he began to slow down. He reckons he was ballpark same height as me at my age, perhaps a little shorter but he really doesn’t know. Worryingly, people at school are telling me that I look shorter, which obviously means that they are growing at a faster rate than me. I have not really noticed it myself, besides in a few cases. I’m worried that I’m following the same trend as my dad, and I’ll stop growing soon. But, what has confused me is that my dad is like, the meaning of skinny, where as I already weigh almost 5 stone more than him, and I am more well-built and stronger. I didn’t know where I got this gene from. I have recently learnt that my grandfather, who I don’t see very often, is actually somewhere between 5’11 and 6’2 (probably landing somewhere around 6’1 at his peak), and, he, to me looks a similar build as me, but, seeing as he is now 80, he is always hunched over and I can’t tell, he is on my mother’s side. Most of the rest of the males on my mother’s side I have met are rather short, shorter even than me, so I was hoping I’d missed that gene. I am also told that, while on my dad’s side, my grandfather was only about 5’8, roughly my height as I stand now, my great-grandfather was rather tall, possibly standing at around 5’10 or 5’11, although, I have never met him and my dad doesn’t remember in detail.
My diet isn’t great, bacon for lunch every few days, coco-pops for breakfast, have takeaways often for dinner, a lot of fizzy drink, especially coke, I’m trying to cut down. I have a glass of milk every day before bed, not sure if that means anything. My sleeping pattern isn’t that great, in school time I managed to get to sleep around 11.30pm-12am, and woke up at 7am, now that it is the summer holiday, I’m getting to bed anywhere between 12am-1.30am, and waking up around 9am-10am.
I don’t really do any sport to speak of, even though I am a bit chubby, I am very good in the pool, by no means in the same league as the water-polo muscular swimmers, but, out of several football and hockey players in my class last year, I was placed in the top swimming group, with the water polo team and all the really sporty people, and I was OK ability wise in there, which leads me to think that I am probably quite muscular, under the fat, or, I may just have talent, according to the teacher, and could be very good if I got fit and really tried.
I did an online height predictor, and it said I could fall somewhere between 5’10 and 5’11, I also did my brothers height. He is 16 months youger than me, and he is about 5’5. The height predictor said he would be about 6′, which, I know it’s pointless, but it has got me quite upset, unlike me, he is a skinny git. I’d like to reach 6’1 as me dream height, 6’2 if I’m lucky, but I’d settle for anything north of 5’11. Do you reckon I ever stand a chance of getting there?
Thanx