I have Invisalign and an overbite. The rubber bands don't seem to be correcting my bite. After 8 months what's next?

I have had Invisalign for 8 months and been wearing rubber bands for at least 6 months. I have an overbite, but do not see improvements. My orthodontist stated the left side is moving slower than the right and now my midline is off, so I'm wearing only the left rubber band for the past two months, but no improvement. My plan is for 48 trays and I am on tray 24 and wearing the strongest rubber band. Will I see improvement? What should be the next step if the rubber bands don't correct my bite?