Feeling Uncertain

I’m very unsure in the things I do, I have a new job what I really like but I’m very uncertain about myself, I know that I’m good in my work but because I’m so uncertain I make mistakes . Because of that i sabotage myself and want to quit my job. I get angry about it and start to make mistakes. That makes me a person that never accomplishes something in the things I do. I hope you understand my English. I wish I could be more sure about myself to finish things, especially for my children to show them to go on with the things they do in life. Do you have a tip for me?