Should I change? Is my friend right? (sorry if it's really long)?

Okay, so my best friend in the entire world moved to Kentucky. She visited me for about a week. On the last day of her visiting we went out to lunch to this place that serves only chocolate. We have been friends since she was 2 and I was 4 and we tell each other just about everything. While we were eating she told me (in the nicest of ways) that I need to change my style of clothing. She said people will start judging me/may have already started judging me based on what I wear. She said although I have a great personality not every guy will go for just that and if I want a boyfriend I should change a bit. I myself know that I am not the most "stylin' " person I know and I really don't know much about fashion. In the summer I wear navy blue shorts and some sort of t-shirt. I wear a lot of t-shirts from this charity I support (my friend said I shouldn't wear those as much). Last winter I basically just wore one pair of black comfy pants with various long sleeved shirts. I myself got sick of this. I get a lot of hand-me-downs from my brother and I feel the money can be spent on other, less selfish things. I say this but I do spend money on video games. My friend said that I should probably wear skirts and more girly things. I don't know if I would be comfy in skirts all the time. I don't wear jewelry much but I'd be able to handle that I think. I did wear a skirt to my other friend's bah mitzvah because I felt she was worth the trouble. To the other bar/bah mitzvahs I just wore a black t-shirt with black pants. My friend said that I looked beautiful in the girly clothing I wore to my friend's party and all black really isn't fancy any more. I don't really care if people judge me that much and probably wouldn't notice if they did. I don't know anyone who openly hates me. I feel like I have a great personality and shouldn't dress just so people don't judge me. However, I sometimes wish I did dress a little bit more girly. I've never gone shopping for myself before and I would feel weird asking my mom if I could go with her/pick out my own stuff. If I did go with anyone, I'd want to go with one of my friends, but I don't really know my size (All I know is I'm not very skinny) and the one I'd want to go with is the one in Kentucky and my other friend either wouldn't be able to come/would never let me live it down. Ugh, I don't know what to do! Any advice? I want a boyfriend one day but I don't know if I would feel very confident in skirts. I'm going to be 14 in a few weeks and my best friend is going to be 12 in a few weeks. Our birthdays are 2 days apart.