Hah, some of the stuff you are saying reminds me of all the worries I had at that age. You are in a strange transitional period where you have memories of younger attractions, but at the same time feel attraction to the older. It will pass and you will get over it. The problem is a person with OCD hyperfocuses.
I remember the sleepless nights, the hopelessness, the conviction that nothing will change and I MIGHT (key word might as the OCD sufferer is in the eternal pursuit of certainty) never GET over OCD. The thing is I did and the only regret left is that I didn't start taking risks sooner in life.
In terms of the whole being too young looking problem I had a friend with the same exact problem. He was able to get over all of it though after he got out of high school. I hate to give you this worldview, but it will be beneficial. Most of the attitudes of your peers in highschool will either be frankly idiocy or idiocy as the result of fear due to peer pressure and social stature. He was made fun of and dealt with a LOT of $#%^ he shouldn't have out of that undeveloped brain phase of other teenagers. Guess what his life is like now though? He has zero problems with women, he is very intelligent and is one of the most interesting to talk to people I have met. Has a girlfriend and is very happy. Just like I was able to get a girlfriend and am very happy at this stage in life as well.
SO to summarize, stop listening to all the high school #######4, YES this OCD can completely pass and those worries you have turn out to be worries other OCD sufferers have. Psychologists really ###$ UP by dropping the ball on not talking about the influence of the internet more. It has created some serious issues for people, and OCD sufferers scan it incesantly looking for THE reassurance that never comes until the sufferer learns to GIVE UP on finding the perfect reassurance.
Stop researching the internet, try asking out some girls (1. yes you might be turned down, it is part of the process, 2. don't ask out girls because of there looks, but because you LIKE them as a person) and learn to be yourself and say ###$ IT to all the people who don't like the real you. I really wish I didn't waste all that time worrying and being anxious as a teenager which is why I'm spending the time typing all this.
If you ever want to talk, feel free to PM me. I've seen pretty much all of these common OCD worries and it has been YEARS since I've ever dealt with those issues.