We all have our awkward periods. Just looked at some of your history. You're not a bad looking guy. Just try to be confident. In high school people tend to get pretty stuck in certain places. (ignored guy is ignored, cool guy is cool, etc.) When you're in college it is typically too big for people to have labels. Plus, you're still at the age where you're figuring yourself out.
Focus on yourself. Start a regimen now--most uni's have a gym. Use that shit.
Just start talking to people. Talking with anyone is good. Start with people who don't intimidate you and get comfortable. You may make some friends this way which is a bonus.
Seriously...just talk to people. Every guy I know who is super successful with women (no matter their looks) it's because they talk to every girl they can and they don't sweat it if they get shot down. If it's clear they aren't interested just say, "Well it was nice talking to you. Hopefully I'll see you around" and move on.
Stand up straight and speak up.
With talking to people there's a fine line to walk--don't lie about who you are when first talking to someone but also don't drown them with details. Letting someone know about the things that interest you is good but don't scare them off by getting into going deeply into the details. First meetings are like interviews--you're both trying to see if you would be a good fit for each other. If they aren't--don't be disappointed. Just say the same thing as above and move on.
Don't say, 'want my penis inside of them' ever again haha
If you're having problems attracting women right now--don't sweat it. Almost every guy feels that way at your age. The biggest thing is to not get fixated on one person and build them up--that makes the rejection hurt more (hard if not unavoidable in high school) but try.
Try not to focus on the 'getting laid' part. Just focus on trying to meet people you get along with. The sex thing follows more easily if you aren't focused on it. (easier said than done).
Try not to feel too sorry for yourself. You sound like you're in the same place me and almost every other guy I know was at at that age so don't feel like you're lagging behind.
As a side note: Pick a major that is marketable--make finding a job easier. When you're in college; girls will date you partly for your potential. When you graduate; potential no longer matters. It's what you have to offer and where you are in life that matters.
I had trouble finding work at first so I got a job at Wal Mart so I'd have some income. I can assure you that not too many girls were interested haha.