Erectile Dysfunction - How 18 Years Old Guys Facing ED Problems

Erectile Dysfunction, is the problem most of the young generation faces due to their regular habits like drinking, smoking, masturbation etc. And sometimes, due to the mental stress, having anxiety, depression, or feelings of shame or guilt about sexual activity experiencing significant stress, about sex or something or having a lack of physical activity using workout supplements and testosterone boosters.

For about a year or so now I've been worrying on and off about an issue that I can't quite understand. I think it could well be Erectile Dysfunction, but I really don't know, because there's evidence to suggest I do have it, and evidence to suggest that I don't. 

I can get erections to stimuli on the screen. Porn, both hardcore and softcore, or even just pictures of girls I know. I don't really have an issue there, although it should be said that a lot of the time I'll need to stroke before anything happens.

The thing that really frightens me though, is that they never occur on their own. At all. I don't get morning wood, I don't get them when I see an attractive girl on the street. They literally only happen if I induce them myself. I'm sure this is not normal and a problem.

I wouldn't say my libido is gone. I'm not as horny all the time as I was when I was 14, but I think that's normal. I still have an interest in sex, because if I didn't I don't think I'd be so worried about this.

I haven't been diagnosed with any other illnesses like diabetes, and as far as I know, everything else is in order. I don't have any other symptoms as far as I know.

I noticed this was an issue last year, but in between that time, it got a bit better I think. They sometimes happened on their own, in the morning and etc. Now though, the issue is back to square one. 

 I've read a lot of articles and posts here saying that it could be pornography that causes the problem. I will admit that I do use it quite heavily, and I've therefore stopped watching it. I've been without it for about 2 or 3 days now and haven't noticed any real improvements.

Last night I was able to get it up from fantasy alone which was an improvement from the night before, but I'd say it was only around 50-60% hard. If I have a stimulus, there are no problems getting it fully hard. To put it simply I have three major concerns.

1. I'm going to college really soon and I don't want to have erectile dysfunction while I'm there. Whenever I get an erection from the stimulus or from fantasy, I get a great sense of relief but it never fully puts my mind at ease. I'm scared that if I get with a girl, it won't be the same story.
2. Could the porn viewing have permanently messed up my brain and this is the result? I'm worried that this may not be reversible.
3. I'm also scared that I may have some other illness and this is a side effect of it, but I've had this issue for about a year now and have had no other side effects. The fact that I can get it up if I really want to puts my mind at ease a bit, but then the fact that erections don't occur naturally makes me reconsider. I think I'm gonna have to go to a doctor over this, but I'm really embarrassed to tell my parents about it. I don't know what I'd tell the doctor either.

Can anyone shed some light on what might be going on down there? I feel completely lost, alone, and helpless in this.