I don't usually comment here but you reminded me of myself when I was younger. 6'3 guard here. You're still young and you'll get accustomed to playing against big guys. If you pay attention you'll realize even the biggest guy out there has weaknesses to exploit. You don't have to be the best shooter or be fancy with the ball. You just need solid and steady handles. Size doesn't matter, if you know what you're doing.

I know plenty of ballers who barely reach 5'8 but they have no problem keeping up with anybody on the court. "Tiny" Archibald, one of the NBA greats, was always one of the smallest guys on the court(6'1, 150) and was a poor shooter. But he was one of the best players. IIRC, he led the league in points and assists one year.

I'm going off point. Back to your dilemma. No hoop or court to practice on? Are you sure? Unless you live in the country, every town and city has courts all over, the local YMCA, etc. There always is a court somewhere. Google is your friend!

If there really is no hoop/court, my best suggestion to do for now is Work out. Go jogging everyday. Biking. That'll turn you in one of the fittest guys on the court and that's incredibly important for small guys who can't just coast by on their size. You don't have to be the fastest, you just need to know when to change speed on the fly.

I remember getting so frustrated playing against the 6'8-and-above guys. I stopped relying on my hops and length which worked against guys my size but not them. I used different moves(fakes, spins, step backs, drive in then kick out for a 3, etc, etc). Millions of moves to choose and study.

You just need to get your foot in the door to get on the team and the rest of your skills (shooting, advanced moves, etc) will come later. Jason Kidd youtube videos would be a good start for you to study. Then Steve Nash, Chris Paul, John Stockton..the list goes on.

Try to not worry about your size, it's out of your control. Focus on what you can do!

Good luck!