i need advice :/ please help

hi i'm a 15 year old girl i'm always depressed angry or sad i tend to have allot of mood swings i use to self harm i feel like i'm alone in this world no1 listens to me when i try ask family members or friends for help they never listen i'm afraid if i carry on this way ill end up self harming again i've even got so angry i have hit my mum before i'm constantly arguing with friends i tend to forget things easy i sometimes have problems sleeping and end up staying up all night and sleeping all day i really need help what should i do ? my sister had bipolar do you think its possible i have the same i forgot to mention well i didnt think i should mention thi suntil i noticed some1 felt the same as me i am always paranoid about my boyfriend we agrue all teh time i usually cause it hes with me everyday day but yet im still paranoid im that bad i sometimes look out my window everytime hes out just to make sure hes not with some1 else im also a very nervous and i have lack of convidence at one point i became agrafobic and didnt go out the house for about 5 or 6 mounths but even know i still havent recovered also sometiems i tend to brake down and cry alot and half the time i dont even know why infact i cry nearly everyday if im not crying im angry .