Wow, you really do have your hands full! The fact that you are aware and know what kind of mother you want to be will go long way towards preventing you from becoming your mother. The single most important thing a parent can give a child is love. They know you love them even if you are detached at times.
You really do need a break, though. A night out, or lunch with a friend can be rejuvinating. Is there someone you can trade babysitting with? A play group? Most community colleges have a child care subsidy program for students who are parents. An art or music class might be just the thing you need.
Hang in there.