I'm a nanny, but I want children of my own

I'm a nanny for a beautiful 2 y/o little girl, I've grown to love her very much. Her parents are appreciative and treat me very well, all of us working together to raise that little girl makes me love my job more than anything. But when you spend all day taking care of another person's child and go home to no children of your own it leaves a hole in your life. My fiance and I have decided to try and conceive but I'm worried about what will happen when we do. I don't want to leave my job and I hope they won't ask me to quit, I would love to stay with them throughout my entire pregnancy and take only as much maternity leave as necessary. Has anyone else had this problem? Either as a nanny or someone who's had a nanny? I love my nanny family but we're ready to have a family of our own.