Do I have ED and what could be the cause?

First of all, a bit about myself, I'm a 17 year old guy who doesn't know whether he has erectile dysfuction or not. It started of a few weeks  ago when I realised my erections where getting softer and softer and also realised I didn't have morning wood for quite a long time. I started to worry because I thought is was a result of over masturbation. (I masturbated to porn every single day.) I decided to give up masturbating for a while and my erections returned. Not having masturbated for about 5 days, I decided to give it another go, and the day after again, didn't get any erections at all. I decided to quit porn for good because I was convinced I don't have ED, but it could get worse if I keep on like that. I didn't masturbate for 4 days, and my erections came back (100% fully erect). It was getting really bad, i would have them at school all day long and I couldn't stop thinking about sex as well. I couldn't hold back mastubating, so I did. I was scared I got myself in this situation again where I couldn't get it up for 4 days again, but suprisingly, i could the very next day. I figured I solved my problem and just had to reduce my masturbation routine to 2/3 times a week. But since yesterday I am experiencing trouble getting erections again. I know it's quite a long story, but I'm wondering, why do I keep having those periods where I can't get hard erections? Do I have ED or is it just between my ears? I am not dating girls at the moment but i do date them quite often, and it would be terrible if I have a girlfriend at the age of 17 who I can't sexually please. Please reply if you think you can help me. (Ps. watching porn is not healthy and I recommend everyone to quit watching because it's not real life, and living in that fantasy might have consequences for your sex life). Thanks for reading this.

I'm not sure personally, but you are in the right place searching for answers. Listen to this radio show and see if anything makes sense for you. Then listen to the rest of them. This site is a great resource.

http://yourbrainonporn.com/porn-sexual-conditioning-and-adolescent-brain-show-17