Does the world really see me, the girl who hasn't even had a first kiss at 14, as a slut?

At my school a lot of the girls wear shorts and tank tops. Some people I know would call them sluts including my best friend. I personally didn't care, so I never gave it much thought till eighth grade summer, me and my friends were all going to different high schools, and I started wearing spaghetti strap shirts, and thought corset shirts were cool as long as they didn't show your breast line. I always hated shorts, but I started liking boots with heels. My best friend considers girls with heels and corset tops sluts, which is why I'm afraid of wearing heels and corset tops, because I don't want to be called a slut. I also tried shorts and they were quite comfortable. The reason I like these clothes is because they're comfortable, not to show my body. As a matter of fact I feel uncomfortable showing skin, and have worn jeans 90% of my life. I have very little self confidence, and am trying to become confident. And whenever I wear tank tops my friends' eyes widen like if it's wrong. Are they being too uptight, or does the world really see me, the girl who hasn't even had a first kiss at 14, as a slut? Like seriously I haven't even had my first boyfriend.