Is it important to be a "master" of something? I think it's more fun having conversations with people who are well-rounded and enjoy a variety of activities. Anyway, you are a "specialist" in a way. How many people have told you that they "could never homeschool"?
With that said, I too feel, at times, as if I have no expertise. I wonder what I'll do when the kid-o's are gone. I haven't worked as an engineer in over 13 years. I have a Master's in Teaching (finished 13 years ago) but have never offically had a classroom (except to substitute). (OTOH - not sure I really want to teach at a ps.) God put homeschooling into my heart, if he wants me to be good at something else, he'll put whatever that is in next.