Is this depression or extreme sadness?

So I'm a freshman now but ever since about 6th or 7th grade I'll have nights where I'll literally cry myself to sleep. I'm not very popular but I'm not a loner either, I have friends and some really good ones too. But I've never told any of them about this and they've never really noticed because I'm usually super bubble and energetic and usually always laughing(to try an hide it). I'm mediocre in grades, mediocre in sports, fairly healthy, I personally don't think I'm drop dead gorgeous but not ugly either. And today my mom and I had a fight and really feel like I'm about to burst. I kind of feel worthless too. Would this be depression or extreme sadness? If it sounds like depression I really want to go to the doctors because my brother is a victim of depression/anxiety and he's had three anxiety attacks and I really don't want that to happen to me.