Fear--or, Why Didn't I Realize this Before?

There have been so many times in the past five years of homeschooling that I have been gripped by fears about the decision.  Not just passing concerns, but true fear--the kind of fear that makes my stomach seize up and makes me feel like I want to be sick, go to bed, and just commit my kids to the big yellow bus to take them where it may.  The fears have ranged from everything from not knowing how to teach my kids what they need to know, not knowing how to teach a kid to read, not knowing how to plan a schedule and stick to it, not knowing how to fit everything in to a 24-hour period and still feed the family, not knowing how all this is going to turn out in the end, to the ultimate fear...am I ruining them?  What if I'm totally screwing them up?  I look at this list and see all the times I haven't known how. 

There's an old hymn that we used to sing when I was a kid that says:

"But I know whom I have believed and am persuaded that he is able
To keep that which I've committed unto Him against that day..."

(I realize this is pretty much straight from scripture, but I always think of the tune) The thing is that God has called me to this.  Of that I am sure.  I have committed this venture and the lives of my children to him.  How can I doubt that he will faithfully care for me in the process?  He didn't call me to know how, he just asks for my obedience.  He knows how to get this done, and he knows the future of my children.  Since he is the One who knows, I need only ask him what they need for each day, and he will provide for the education of my children.  I have to believe that he has asked me to do what is best for them, and that means that I am not ruining them.

As I talked to a friend today about these fears it occurred to me, "what fear is there in having your children with you, learning and growing?"  On the contrary, it should be more fear-inducing to send them out into the world as young as we do.  Fear is not of God, so it can only come from one place.  And all this time I thought it was my problem--feelings of inadequacy and what-not.  Humph.  Not so much.  Why didn't I realize this before?