Hello, I am 33 years old, female.

My teeth suffers from dark black stains usually found in the spaces between my teeth and in the crevices on my teeth (like craters).

I do not smoke.
I don't drink coffee/tea/cola too often or too much. In fact, I only drink these beverages when there are no other options available. My preferred drinks would be water or fruit juices.

When I was much younger (late 20s), it would take about 6 months before the stains would return after I have had them cleaned.

Now, at 33, and I see stains forming in a couple of weeks after I get my teeth cleaned. And I have to wait 3 months to get them cleaned again. They are causing me a certain level of stress because they are very obvious. They prevent me from smiling. They make me conscious when talking with people. And recently, its formed sooner and quicker than I expect them to and I always wish my 3 months was up so I can have my ugly stains removed.

My teeth have no plaque nor tartar. Only these dark stains.

I brush and floss 2 to 3 times a day, everyday.
I use a whitening toothpaste (aquafresh extreme clean).
I use an electric toothbrush (oral b).

To my surprise, recently I have read that apples and potatoes can cause stains. What other fruits and vegetables cause dark stains?

And is it just food that's causing these stains?