I do hope you talk to her about your feelings. She very well could mean what she says as a compliment to you, but it's just coming out the wrong way. She probably means that you are very competent and good at what you do.

I would tell her that you appreciate her concern, but you love your job so much, and having the opportunity to interact with such great kids, like her son, that you can't imagine leaving it. Tell her that when she says these things to you, it makes you feel bad, like your job isn't important enough as it is. Ask her to stop suggesting these things.