Hey,
You have every right to be self-conscious about your appearance, as it clearly plays a role in almost every social situation. But you know what? Your looks are not permanent, and with the right kind of mindset and dedication, you can come out as a new man in as little as six months. Believe me, I've been there.
There's this saying: "You feel the way you look, and you look the way you feel". You cannot treat your inside and your outside independently. That being said, I can totally understand the vicious circle you're in. Well, if you want to change for good, you have to break it one way or the other.You can always try to approach the problem from the inside, but believe me, it takes way more dedication and way more time, and the results are not that obvious, so you can get easily frustrated. What I suggest you to do, is to start working on your appearance.
And no, I am not talking about getting some stylish clothes and a stylish haircut. Way too often do I see people who try to intimidate others with their choice of clothing, only to look in their eyes and see a scared and insecure person. It might be a temporary solution, but it sure ain't gonna stick. Nor am I talking about using facial products etc. etc.
What you got to do, is to start exercising regularly and do LOTS of cardio. It doesn't matter whether you run, swim or bike, as long as you sweat your ass off. Commit to a strict and hard routine, and follow it. Not only will it develop your body and your muscles (on a side note, I am also 5'8, and i have never thought of myself as short..), cardio is one of the best ways to combat acne, and it also rejuvenates skin. In addition, spend as much time as possible outdoors in the sun. You could always go jogging, or if you don't have any ideas what to do outside, just take a book/lecture notes and head to the park. You'll get tanned and you'll get a healthy dose of Vitamin D. Commit to a hard routine and a life outdoors for three months, and I guarantee you'll see your body structure changing, your skin starting to glow and your face clearing up. Just forget about the chicks for now, and enjoy building yourself to a man you wish to be:).