Some things to keep in mind, Are you already slim or skinny? Would you say you have a fast, medium or slow metabolism?

At your age, if you're on the fast or medium metabolism your goal should be hitting the 2-2.5g protein per kilo of body weight (metric here) and be less concerned about calories as long as you really don't over eat (assuming you are medium metabolism... Fast metabolism at a young age when working out is basically a free ticket to eat until your late 20s :P)

If you're on the slow side? Calculate your TDEE, download MyFitnessPal and start logging your meals and checking your daily calories. To lose weight while building muscle you would need to be at your maintanance or a bit below it (200 calories or so) whilst maintaining high protein. It varies from individual to individual so really it comes down to finding a calorie limit, sticking to it and checking week after week how the scale moves and adjusting accordingly - no one here can 100% estimate that for you, it's through a bit of trial that you find out what works for you.