I'm an 18 year old guy that wants to look older than he appears, any help?

Hi, I'm 18 years old and honestly I look like I'm 14, I just graduated high school and I already have a great job as an STNA making $14 an hour and I'm currently attending college to get a degree in nursing. I have have my own car that I already paid off, I have a ton of money in my bank account and if I wanted to I could pretty much live on my own and have a lot of luxuries to go along with it. I'm not bad looking (except for a few zits but they will dissappear in time...) I pretty much have everything I need to be considered an adult and what not but the only thing iIs my appearence, I look SO young that no girl shows any interest in me what so ever and unless they're like a pedo then they don't view me in any type of an attractive way, it affects me too cause I feel like I can't be good enough to impress anyone (I'm shy), I don't normally let things like this get to me but it's been puting me down a lot latley. Mainley because I've never had a girlfriend and I feel like if things don't change then I'm going to fall to the back of the "pack" and never find that special someone because I will have had no experience with girls in that type of manner.. what should I do? How can I look older and what should I do to make a productive approach into solving a problem like this? thanks all :)