I'm a teen myself and yes, it's very normal. These teen years there's just a lot of things going on in our lives that can be stressful. For example school, friends, hormons and other things are simple reasons that can cause a depression. However, your friends and people around you should treat you fairly and not make fun of you and then expect you to be fine with that just because you're 'too nice' sometimes. You could maybe try to show the people being mean and making fun of you that it hurts? You could for example say something like "that's actually offending me" if they say anything that you think hurts you.