Dating Quandaries as a Nerd?

Ever since I was young academia has been a top priority of mine. My parents always instilled the idea that education will take me as far as I want to go in life, except socially. As a result of pursuance of higher education and overall knowledge I feel as though I've missed out on the social aspect of my life. While I have friends from both high school and college (which I am currently enrolled in as a student of Mechanical Engineering), I have never had a girlfriend in my entire life. I'm 18 and all of my other friends have been in relationships or random "hook-ups". I feel like an outsider in some respect or another. I'm incredibly nerdy, shy, and serious at times. However, from what I've been told, I have quite the outgoing personality and sense of humor, and that I simply need to let it show more often rather than when the occasion calls for it. Friends of mine are determined to get me a girlfriend by the end of the summer, but I personally feel as though they're going about it the wrong way. They're trying to change my look (which for me is a facet of who I am). I'm a very simple guy who enjoys jeans and t-shirts with various science fiction pop culture references. I don't want to change myself for sake of being with someone, especially what makes me ME, whether if its intellect, dress, personality, etc ad nauseum. While I agree that I could use a little tweaks here and there I don't think an entire wardrobe change will suit me well. I'm simply a nerdy who gets incredibly lonely at times. Not even finding solace in Mathematics or Science can help me. There are girls out there that I am interested in but I'm too shy to vocalize how I feel about them (because I have a deathly fear of rejection). I'm not sure I know what to do. I'm lost. Can someone please help me?