Disappointed RN

I went into nursing because I wanted to help people and make a difference with my life. I'm intelligent, kind, and hard working. I should be able to be a good nurse, but I just feel like a failure most of the time. I feel like nothing I do is right. I get chewed out by doctors (often for things day shift missed and I had to call about in the evening). I get chewed out by the nurses on the next shift, in front of the patients. I try so hard, but I leave every morning depressed. I have palpitations at work from the stress. I spend more time with my coworkers than my kids, because my boss insists I work overtime. I just don't know if I can take this much longer, and I've only been working for six months! More than anything, I just really wish I'd never went to nursing school. I was so excited to have that degree, and my family was so proud. Now I'm just sad.