You might get sick of hearing this, but you're young and if you fight it now it's a slightly easier battle. Personally I had PMO issues for just under a decade.
As far as advice goes the most effective method is fasting. Especially because you're at a age where you're testosterone is being produced rapidly. (It is more effective in summer imo)
Work out. You're young so don't do weights and bench presses. I'd suggest calisthenics. You can buy a pull up bar (no screws) (there's obviously other ones you can buy). If you're new to it start with a routine of pull ups and push ups. The reason I suggest this is your at a age where you body will find a way to burn energy one way or another, Even if you're not "athletic".
Hold on to your Salah. The spiritual benefits I am not able to summarize, but from a habitual point of view it creates a routine. And before you pray you can't be in a state of major impurity. Hence there'll be times where you thinking of PMO but you might not because you'll think "ah I'll need to do ghusal anyway because it's magrib soon" which will deter you from PMO.
May Allah (swt) make this a test easy for you. insha'Allah the more you fight against it the more you'll be rewarded.
Long time ago I had an over the door one like this
It was rock solid, only left slight scuff marks on the door frame
This is my doorway and this is the pull up bar I bought.
Will it fit in my doorway? I didn't really have time to research as I bought mine from an auction on eBay. I'm 16 and have barely any money so I didn't want someone to outbid me for the price I got mine for.
Will I have to return it?