taking adderall has probably messed with your metabolism if youre still losing weight, exercise more and switch to a high carb diet ( eating average size meals 2 1/2 - 3 hours apart) and if you dont have time to eat that often, have something like a high carb protein shake 1-2 times ( not too close to your other meals, as they can cause bad gas, and possibly stomach aches)

if you wanto put on weight, don't just eat more as it will most likely just get stored as fat.. the human body is stubborn, you need to give it a reason to wanto grow! so make sure you're doing a decent amount of exercise along with your diet.