Am I too old for Elastics too work? (photos)

I had braces 4-5 years ago. I'm 20 now, and some late jaw growth has caused my jaw to slip forward a few millimeters . Because of my malocclusion I've had some jaw tightness and a bit of pain at times (usually because I keep clenching my jaw during the day because of the bite). I went to my ortho andd discussed invisalign/elastics but he said that since I'm older now my jaw could slip back out. He discussed shaving the teeth to make some room instead and move the teeth more.

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