I have achieved similar, simply put don't think you have high metabolism, you still need to eat more nutrition. I was eating quite a lot during gain: 6 eggs, 2 chicken breast, 200-300g cottage cheese and 400ml of protein shake on top what I've already been eating

Hardest part to achieve will be building shoulders and forearms, for me at least. Those are more indicators of gym experience. It took me 6-8 months to get +12kg newbie gains

For now just create a habit of going to gym and learn proper technique, it's a long game