Ok first thing to consider which will instantly make you hate me.
You are 12 years old, first or second stage puberty at most unless dangerously early developer. this is a period when you will need energy stores to fuel an unpredictably varied development from boy to man. Not having the fuel you need will (not can) delay your development. The effects are generally temporary but if taken to far can be permanent.
My son is just a little younger than you and he is likewise wanting these symbols of perfection too, so yes I do know how little you want to be told this.
The only way to have a full visible six pack is to carry very low body fat. My abs are far stronger now than they were when I had one all the time. I now range between an occasional six to a one pack dependant on my training, and it's never there when I am fully relaxed. It doesn't make you stronger or more capable, it's pure image.
There is a growing pressure on people to look set ways but what you are seeking is something that is best leaving until you have finished puberty. Be relatively lean by all means but not this far when your body can demand fuel at any time. Go for ability for now, in a year or two you will have enough acne for your abs to be the least of your aesthetic worries, so be fit ready for when you can really look good.
