I've had braces for almost 2 years. Why are my last teeth still sticking out. My ortho seems to be already "satisfied." (photo)

As you can see, there isn't any bracket on my last tooth. I did point out to my ortho but he said the back teeth are difficult to move & it's okay to leave it as it is. He also told me not to worry as long as the biting is correct. I was somewhat convinced till recently I've been experiencing serious biting issues such as biting my own cheeks both left & right (causing ulceration) It's beginning of Nov now & I was told that I can take em off by Nov or Dec. Can this be corrected within 2 months?