am i pregnant or is it just depresson?

okay i am depressed angry and tired all the time i am trying to get pregnant and it has been over a yr i am going crazy, i dont know what to do im not sure if i am i am almost 2 weeks late but i have been late many times before, i dont know if i have a depression problem because i am always angry and sad feeling not good enough and i feel i cant have a baby i have 3 already but wanting more am i too stressed out i try to be calm but its hard