Help with WHITENING TEETH (preferably to be answered by a dental hygenist/ dentist/ orthadontist)?

Here's the situation. I have ALWAYS, since the day I got my braces off, taken excellent care of my teeth. I'm 22 years old and have never had a cavity. Flossing, brushing, Listerine mouthwash 2x a day, the whole 9 yards. A couple of weeks ago I started to notice that my teeth looked a little stained but I didn't think it was that bad. I went for one of my clean-ups and I wa told that my teeth were stained a fair amount. I NEVER, EVER drink coffee. I do NOT drink tea or wine very often. I only have soda on a blue moon when I have pizza. And as far as juices go, I only have ONE cup of orange juice in the morning and ONE cup of either apple juice or iced tea with dinner. The rest of the day I drink (lots of) water and maybe milk here and there. The dental hygenist was shocked when I told her this and said the staining may be from something in my saliva but my diet (which has fruits, veggies, everything right) hasn't changed much so I don't see how that's it. I've been using the listerine whitening mouthwash and I tried the Listerine Whitening disolving strips for the whole 2 weeks you are suppossed to use them. I see some difference but they haven't cleared up completely. Any advice on how to get my pearly whites back? Thank you!
--------------------
There are many products that you can use to whiten your teeth. Whiten mouthwash and strips certainly will help. It will take some time, you will get your pearly white back soon. Also one more suggestion would be, brushing your teeth with baking soda. My family had been doing that for quite some time now, and it definitely helps.
Source