Why do they consider ME a slutt?

So basically everyone in my circle of friends has lost their virginity. I just did a month ago to my boyfriend of three years. We're all 15 in 9th grade. So why is it that I had once, got pregnant, and I'm considered a slutt, while my best friend has every night, and she's not even dating the guy she's sleeping with. I had a miscarriage, so I'm no longer pregnant, yet I'm still considered a tramp? And all the guys think they can sleep with me and that I'm easy. My boyfriend is really protective, so any guy who says something mean to me, he pushes them. Normally they push back and they get into a fight because of ME. And the girls give me dirty looks. I haven't had after that first time, but every single one of my friends do it and no one says anything. Why is that? Is it just because I got pregnant? Oh and at least me and my boyfriend used protection. My friends don't.