Kids Reading is Advanced

I have three children. My youngest child is three years old. My other two children are school age. I started my middle child in public school and I did not like the change in her behavior. She does not seem happy at all anymore. I am seriously considering homeschooling all three kids. I bought a phonics reading program a year ago that all of my kids use. They love it and my middle child is reading way beyond her peers at school. I think maybe part of the reason she doesn’t like school is that she is bored. When she shows me her homework it is well below her capabilities.