Not ready to be responsible?

I'm only 18, with a grade 10 education. I have no parents I can live with and rely on. My parents live in different provinces. They don't help me financially. I don't even speak with them that much. I live with my sister, but it's a hostile environment. We fight a lot so I'm searching for an apartment. I have a full time job that pays alright. I make around 1300$ a month. I'm scared to get an apartment because I'm Only 18 and still a little immature and irresponsible at times. I'm scared I won't be able to keep my job; it's my second job, been working there for over a month now. I feel like I will never be able to get ahead in life. I still have half of grade 11 to finish as well as my grade 12. With work I barely have time to do school work. I feel like I'm stupid because I never finished high school. My reason for not graduating wasn't just laziness. I went through 2 years of severe depression. I don't know what to do right now. I'm scared. There's too much responsibility with getting my own place. I need some advice or stories to inspire..