Libido can vary from person to person and from time to time. It's not just because you're a certain age you're ready to have sex every day. There's many different factors that can influence your libido. I don't know how harmful your porn addiction has been and how your recovery has gone. You write you still masturbate, maybe try some time without? It can also be many things not neccesarily related to your libido itself directly. How is your general mood, how are you feeling, are you eating healthy, exercising, how is your relationship doing, is sex really your goal or other things.
Porn addicts tend to have a high libido because it's been supercharged by porn. Porn offers unlimited sexual partners and therefore opportunity = reward. Realising reality isn't like that has an effect on the brain, perhaps you're just coming closer to your actual sex drive. Additionally sex isn't just about the physical part, but also the intimate bond with your girlfriend. Is it just for lust, or is it part of a healthy relationship?
There's so much that can influence your libido, I'd think a bit about yourself, your life situation, your loved ones, and your addiction. From these few sentences you wrote nobody can really have a solution for whatever is bothering you.