What causes saddle nose deformity?

I have a few questions. I went to get a septoplasty and turbinate reduction and now I have a saddlenose deformity. Is this caused because the ENT didnt take correct percautions or is it purely chance? Furthermore, how should I approach this with my ENT? Should I ask him to do a cartilage graft or go somewhere else for it? Ive already asked him about it and he says he doesnt see much of a difference- but I do notice a significant difference. And I cant afford a rhynoplasy…