Roomies can make it hard....especially if she is your baby. I potty trained Scooter the same way you are, with a stern voice. He knew right away what he was doing was wrong, tucked his tail and head, and came over begging for forgiveness. Everyone has their own method of training. She is your dog and if that is how you feel you should do it and you feel like you are seeing results, be patient and continue. My brother used a much harsher method with his dog and that works for him and Crispy (his Cairn).
At 11 weeks, be patient with your baby. It will come and as long as she is making baby steps to do better, you are doing fine. If you have already taught her to sit, shake, rollover, etc, you must be doing something right.
Potty training will come with time, be patient and don't let your roomie get to you. You will move soon enough and continue to spoil your baby.
