Aww gee I'm sorry that happened. To me it sounds fixable. as they will have to pop out a dent repaint the area and replace the bumper (as well as check tail lights and trunk and other hidden gems under the surface). wouldn't surprise me if it was a 5 thousand or more job.

A GOOD body shop will be able to repair it so it can't be noticed.

The car still drives perfectly fine and the turn signals work fine and everything

If they are a decent body shop, it should not be a problem.

I've had a 2014 honda civic ex coupe for just 3 months and It was rear ended then hit on the back side of the driver side just behind the door and has a big dent with paint that came off and some from the other car. On the back of the car the bumper fell off but it doesn't seem like the damage was too bad. If I take it to the auto body shop would they be able to fix it so that the damage becomes completely unnoticeable?