Why does the left side of my mouth feel like I'm biting down on the tooth after a bonding filling procedure?

in my opinion, you should not be waiting for the bite to become normalized on its own but rather you should return to your dentist for another bite adjustment of the recent composite filling.  

You need to see your dentist again and get it adjusted till you feel comfortable with your bite. You need to repeat this process on that visit.  So, that you can go home and be comfortable. Don't be shy to tell the Dentist that its still high.