For a while now I've noticed it more and more. It just seems creepy to me. I really don't understand the fetish with teens in porn.

That is because you are a victim of the male version of slut shaming. See feminists have shamed men into submission when it comes to owning the fact that ephebophilia is completely natural and healthy. We are biologically driven to be attracted to women that are close to puberty, because they are more fertile and likely to bear healthy offspring. That doesn't mean that it is okay for a grown man to have sex with a teenage girl, but it is perfectly acceptable for him to be attracted to her. Teen girls have the proper physical proportions, perky breasts, and clear skin that signals they are a good mate, and that is what attracts men.

You have fallen into the trap that says that simply being attracted to a post-pubescent but underage girl is creepy and makes you a bad person. It doesn't and that is a flat out lie, it makes you a healthy heterosexual male. Now if you proposition a teen girl or otherwise leer at them, then you are a creep. Simply finding them sexually attractive is nothing to be askamed of.

I don't know. Its possible I guess but I don't think its likely.
I made this decision on my own without anyone talking to me about it.

Really you have never been around another person that described the behavior of being attracted to a teenager as creepy? You have never watched TV when someone if portrayed as a pederast for being attacted to a postpubescent girl? You never saw American Beauty? Media has formed your opinion of yourself. The social stigma created by the feminist zeitgiest has defined how you feel, you never had to be told you have been shown since the day you were born. You learned to be ashamed of your own behavior without ever thinking about it.

A question to make things clear. When you see a nude 18 year old girl with a perfectly toned and proportioned body and perfect hair and skin, do you get an erection? If you do then you are an ephebophile. I am sur you do, because it is biologically programmed into all men. the creepy feeling is because you have also been programmed by society to feel bad about your sexuality, which is the primary goal of feminism