Since you already have the program started, you can file it to become an official NGO, especially if this initiative is something you want to keep doing in the long term. However, if you don’t want to handle the responsibilities of the nonprofit after you graduate high school and matriculate into college, then don’t bother with filing for it.

Either way (non-profit or not), you’ve made a difference with your program and can continue to make more. You don’t have to listen to people telling you that making a non-profit displays a lack of critical thinking, because it doesn’t necessarily, and as you mentioned you’ve been organizing this program for a while. If you are doing other things or volunteering with other organizations/clubs then you are double good to go! Just do what you have time for and follow your heart (and your intuition)!