American immigrant visa problem! Heroes, do me a favor ~

In my experience, I went to the visa three times. The first time, I said I had to make up the materials, and the second time, I said I would have to wait three months. However, I actually waited for almost four and a half months. Then I received the letter and sent it directly. So if they tell you to give you an answer within three months, you have to wait patiently. By the way, it took me half a year from the first visa to getting it. But there is a gap.