What do I do in this case, is this Kufr?

I remember around three-two years, ago in a fit of rage, I insulted Allah, most merciful, most gracious. (I’m currently 15.) Now, I’ve been anxious to my mind,and have been having very bad thoughts because of my stupidness and have been in despair. How will Allah forgive me for this. I have repeated my shahada, performed ghusl and prayed salat-al-tawba, and have been trying to stay consistent with the 5 prayers. How may Allah forgive this. Astagfirallah.