Holly, you are under the care of a mental health professional. Listen to them.
Your priest meant well, but it was not an appropriate penance for you. He likely did not understand your mental health challenges.
If a priest tries to give you a penance related to the internet in the future tell them you are under the care of a therapist and cannot have a penance related to the internet as that is part of your mental health issues. Ask for a prayer you can say as your penance.
Your absolution is not contingent on the penance. You made a good faith effort, there is nothing more to do regarding the penance from your past confession. Be at peace.