be (one's) own master
To not be subject to or controlled by others, especially at work or at home. I have to be my own master, so I couldn't work in a big company like you and have to answer to a boss.
be (one's) own mistress
Of a woman, to not be subject to or controlled by others, especially at work or at home. I have to be my own mistress, so I couldn't work in a big company like you and have to answer to a boss.