Am i going through a mean faze.?

I turned 18 in june lat year. Everything was great after high school graduation until the typical slap in the face from reality hit me in September. Aying for car insurance, working 39 hours a week instead of being able to go to school upsets me all the time. I'm becoming more meaner than ever too, i'm always too tired to go hang out with friends/ family. Im alwys getting into arguments with mostly my sister. When she walks away i feel bad cause the words spill out of my mouth and all i do is argue. I alo cannot stand it when someone jooins in the family room when i wad the first person sitting the, everytime i think about it i think about how ridiculously mean i am. I don't want to be like this.