Is it normal that i get really depressed for no reason at all?

Sometimes i just get so sad. never to the point where ill kill myself; i would never be able to bring myself to do it. but i had stopped cutting for a while and recently the sad feeling came back. i had been able to control it and fight the urge off but eventually i broke. i am alone alot, and i know that is part of it but i know this is not normal. sometimes i get sad over stupid things that normal people wouldnt thint twice about. i try to spend less time alone but then the time that i do spend alone, im thinking about something i said wrong or did wrong and it makes me so mad. sometimes, for no reason at all, ill get so pissed and start flipping things over and breaking stuff. i need to be able to controll myself but its so hard. i just want to be happy...i try to but sometimes its hard. and i normally am happy all day... but the depression is killing me. ill get sad for no reason what so ever. is there some way i can control these feelings? is there something wrong with me?