Do you know your vertical measurements?
Honestly, you're worrying too much about over-doing it. I would say, you should take some days of basketball out. 4-5 days of basketball is great if you want to get better at basketball skills, but not great if you want to make good athletic gains in that short amount of time. Play 2-3 days a week maybe. Unless of course, your 4-5 days a week are like 1-1.5 hours each and you are not really fatigued by it.
Anyways, weight room buddy. Squat, and do some glute/ham/p-chain work like dead lifts or GHR's. Having a lower body weight room day 2x a week is sufficient for you. Also add some calf work, body weight or with weights if too easy.
Let's say you start squatting and after 2-3 sessions of squatting and learning the movement. You have a 1 rep max squat of 200 lbs. If by that tournament you're squat goes up to 240 lbs, providing that you are consistently playing basketball during your training to keep your bball movements sharp, and providing you are practicing jumping/some plyometrics to keep those strength gains converted into power, you will be more explosive. The more your squat goes up, the more explosive you should be.
Some people will have there explosiveness/athleticism go up linearly with there squat numbers, while most people like me, will not. Our athleticism and explosiveness will go up as we do some plyometrics as well, to convert the newfound strength into speed/power.
It is simple, but don't expect magical transformation in that short amount of time. However you might gain a decent amount, since it will be newbie gains.
Good luck.
Also, eat enough. Don't overeat, but eat fairly enough to keep gaining strength and etc.. Rice and chicken sounds fine. Chicken for protein, rice for carbs/energy that you'll need at your age
. If you modify your diet nicely and keep up with this routine, you will also get leaner, which itself will help you become more explosive.
