Why am I so flipping angry all the time?

Lately I've been having some problems with my family. I'm the I'm 14 and I'm the third youngest and so my older siblings like to pick on me a lot I feel unwanted and not cared about by them. I wish I was a only child all the time because of them whenever I'm with them they make super angry beyond belief. I'm also get really depressed when I'm with them which I think might be some sorta serotonin disorder or something. I never have any anger issues when I'm just with my parents which feels like such a relief to me. They're always making fun of me and when I try to fend for myself I end up crying for no apparent reason which I hate because they make me out to be an oversensitive loser. When ever we're around people I have social problems and no confidence in any sorta activity when they're watching. any advice do I have some mental problem or anger issue is this adolescence or something. I've considered lots of things but I can't come to a conclusion.