I didn't mean to imply that baking soda would remove your stains. I just wanted to set the record straight on brushing teeth with baking soda.
Recently, a friend of mine, a former smoker, started OP in hopes of whitening her teeth. So far, after 2 months, she has seen no results. If you are successful eventually, with another method, please post and I will share your experience with her. If she finds a way to whiten her teeth, I will let you know.
I hope you find something that works.