HK couple with a 9-years-old son looking for helper

We are a HK couple with a 9-yrs-old son living in Yau Tong (near Yau Tong MTR Station). We are both working, so that we need a helper to take our son to and from school and cook dinner. No elderly, no pet, no car and no garden with us. We hope that the helper can watch our son to do homework and talk and play with him while we are at work. The helper also needs to go to market and cook dinner by herself. She will share room with our son. Day off will be of the pattern of two Sundays and one Saturdays. Special requirement of day off can be discussed. We are a small family and the housework is simple. We are nice and our previous helpers had all worked at our home for more than two years.