Is my overjet really only 2mm? What can I do, if anything, to reduce it? (Photo)

I had Invisalign 5 years ago for 1.5 yrs. my teeth have either shifted since or my jaw developed. I recently got a new dentist. I'm not so sure how I feel about the answers I am given. My dentist said my overjet is 2mm and my overbite is about 30%-40%. To me my overjet looks to be more than 2mm. If that is the case what can I do to minimize that? Surgery or extractions of any kind are not an option. And I feel as if my retainer is loose and doesn't really keep my teeth from shifting.