I think you have to address your insecurities first. How will you get over that? Once you are happy with who you are, what other people say about your wardrobe will not matter. If you think that changing your fashion sense will make things better, then ask the help of a trusted friend. Sell some of your old stuff to buy new ones. Before you change everything, try on a new look and see if you are comfortable wearing it. It would be a disaster to have new clothes you don’t feel like wearing.