You are wasting your money with whitening toothpastes, they will never work, but may be useful to maintain the effects of professional whitening.
I had Zoom Whitening done 2 years ago, costing �300 (Special offer at Erotica London) and it was reasonably effective, however, my teeth were not particularly stained or discoloured prior to treatment.
I would not have it done again as it was one of the most unpleasant experiences ever. I had to sit in a chair with my mouth open, in front of an ultraviolet light for an hour. Afterwards my teeth were hyper sensitive, so much so, I had to take painkillers for 48 hours. I couldn't eat, drink or sleep as I was in so much discomfort.
You will see more results with professional whitening, than you will with toothpastes, so perhaps treat yourself at Christmas and have it done, if it's what you want.