https://www.mentalhelp.net/adolescent-development/caloric-requirements/
I’m not a Dr nor do I play one on TV. But my uneducated guess is to up those calories.
You may want to research that a bit more. Also, you’ll still be making more mussles and you probably will want to see some weight gain with that.
I agree with @Jill_Carpenter
I am certainly not a doctor either; but I don’t think that you are taking enough calories a day for a 16 year old that is still developping and growing.
From my past history of a serious eating disorder when I was in my teens, I would highly suggest that you don’t focus on calories; but instead on being healthy and eating Keto approved foods (certainly!) but don’t worry about calorie counting so much.
Keep in mind, this is a public forum. While it’s wise to associate in a group with the same interests, and while we can toss somewhat educated guesses your way, everyone is different.
You’ll need to research and it’s super important imo that you make sure to get all your nutrition goals met in growing years.
Weight lifting requires a lot of calories. I think this may be why you are feeling lethargic.
There’s a careful balance as if you’re not getting enough fat your body can start breaking down your mussles.
Talk to your parents or who ever you need and see if you can align with a Dr or even a nutritionist who will be better able to help you define numbers to follow. 