4 years with braces and teeth are still crooked. What do you think would be the best treatment? (photos)

I have had braces on for 4 years so far and although it has gotten better since the beginning, for the past year my teeth have not been moving. The front teeth are slanted toward one side, and 2 teeth stick completely out, where the back of the teeth touch the bottom front. They also flare outward. My bottom teeth are crooked as well. I haven't had any teeth extracted, my dentist did not feel the need to. What do you think would be the best treatment?