Is this depression or something else

Well I'm 18 and a girl so not stupid crap about 'its just your period' please, thank you. My is it normal question is that I'm have really sad feelings when I'm alone, when I'm out with friends I will be loud and having fun but once everyone is in bed and I'm alone my mind starts going to things that up set me like how I don't know where my future is going, how iv only ever had one boyfriend and the relationship was horrible, that iv been used for sexual things by boys who I though were childhood friends that might have cared about me, how my older brother has moved back in to the house with his son and we were sharing my room, now iv slowly been moved completely out of my room and now sleeping on the couch. Iv never had high confidence about myself or things I do no matter what it is or how well iv done something I won't thinks it's good enough or that I'm good enough. Iv asked for help regarding anger as with 5 people in a bedroom house gets stressfull and they just say nothings wrong I'm normal but getting angry to the point of hitting something can't be good. I have had thoughts about suicide and what people might do if I did (not that I would) and how it might affect people or if it would at all is this depression or somthing similar and any tips on how to help would be nice thank you