For my case is there any other solution rather than extraction of teeth? (photo)

Hi, I have recently visited an orthodontist for braces and he told me that I need four premolar extraction from the upper and lower jaws with 2 years of treatment, I'm very confused and I want your opinions about that..I would like to mention that I'm 23 year old and I had braces before 4 years ago for my upper jaw only but it fails because I received my retainer very lately and it did not worked well after all as I hoped.. Can this affects on my teeth if I have a braces again??.....thank you