I don't think there is any such thing as a "normal" height for a 12 year old, or a person of any age for that matter. At 174cm you are above the average height for someone your age for sure, but that doesn't really mean a great deal.
Kids mature physically at different rates and at different ages. This is dependent on things like hormones, which affect growth rates, and genetics - the genes you inherit from your parents.
Sometimes, an increase of certain hormones early on can lead to a growth spurt, which may cause you to appear a lot taller than your friends and peers now, but it doesn't necessarily mean you will continue to grow at this rate.
Growth tends to happen in fits and starts and this is normal, whatever your height, so don't worry.
Besides; there's absolutely nothing wrong with being tall!
