Rebooting help

Hello everyone!
First time here, and a bit scared to be honest. My story is simple: I´ve been masturbating since I had 15 years old. Nowdays, I´m 24. Fapping turned my life to ruin. I don´t consider myself an addict to porn, despite the fact that i´ve watched hours and hours of it in the past, but the thoughts in my head, or memories of sex time, anxiety, moved me to masturbate at least twice a day.
A few days ago, I decided I wanted to change my life, and stop fapping.
Which is my problem? Actually, after 5 days of no fapping, I couldn´t get an erection easily. I noticed it after kissing a long time with my girlfriend. I was with her, but nothing happened to me.
This was yesterday. Then, today, afraid of not-getting-a-good-erection-in-my-whole-life-again, I masturbated again. It costed me some time to get an erection, and it wasn’t as easy as it used to. My dick wasn’t even hard as usual… So, here comes my question, is it normal? Can I recover from it? I´ll be trying the 30 days challenge… but i´m scared man.
I read a lot of stories of this here… but I´m a little bit scared of not having my dick hard again, and be ruined at the age of 24. What a waste.
Thanks to everyone.