Hi Mai_chan... Let me try to give some corrections and suggestion on your passage. Here it goes. :)
Deciding to move to another house is a big upheaval for the entire family . At first, I thought it would be hard to forget about the old(previous) one , but when Icompared(comparing to) them , they seem different in a pleasant way(they have different way for pleasure) .
One of the differences(alterations) is (about our) privacy space . In my old(previous) house ,The rooms were tiny and close to each other , and I had to sleep with my two sisters in one room . Unlike the new one , It has two stairs and the rooms are more beautiful and wider than the old one . I have my own room and its(privacy) bathroom that nobody can share it with me(I do not need to share with the others) .
To sum up , T(t) here are advantages and disadvantages in both of them (1) , but I prefer the new one because the streets are less noisy and the neighbors are friendly and I am satisfied with it.
1. I do not find your statement about the advantages of living in your previous house. If you mention it in your conclusion, you have to explain it in your body paragraph. :)