trying to quit masturbation and porn

(15f) have been struggling with it for years ever since i discovered it. every time i do it i try to convince myself it isnt a sin or some stuff like that just to validate myself for the moment but i always have this crushing guilt after and i feel like ive gotten further and further away from God.

ive tried to quit before but i can barely make it longer than a week before i cave again and im just asking for some resources and help on how to quit.