The more stuff you cough up the better. It is better for it to loosen up and come out of your lungs. Be sure and drink lots of fluids. This will also help to thin the mucous out. Coughing to some extreme is actually good to help clear your lungs.
I also would like to say that I have two dogs that are inside/outside pets.
The way I deal with pet hair/dander is I vacum daily. Dogs get bathed once a week. I also use my swifter dust cloth on them a couple of times a day.
This helps to remove pet dander, hair, dirt, and any pollen they have picked up outside. When my son was younger, we were advised to remove the carpet in our home. That lasted for six years. As he became symptom free for long periods, we decided to give carpet a try again. Even his physcian agreed that getting rid of the family pets would do more harm to our son than good. He was allergic to everything so his allergy shot included pet dander as well.
I hope this helps some. Let us know how your appointment goes tomorrow!