Should I be able to move my forhead after botox?

This is not your fault. Results are dependent on the injector, and she may not have injected the appropriate amount of Botox into the areas being treated. I recommend following up with her, and if she is a new injector for you, discuss with her the typical amount of Botox you have received in past treatments, and possibly take your medical records to show her this.  Adding more Botox is an easy fix, but let her know for future reference that you prefer no mobility in your forehead. Hope this helps!

For some patients they prefer some movement of the forehead, most people don't want the frozen look, but in your case it seems like you are freely moving your forehead more that what you would like. Follow up with your injector and explain that you do not want to see any movement to the forehead. It may just be that you need more units to get no movement. Its an easy fix. Hope this helps.