Is it possible to whiten teeth when your teeth are weak?

I wonder if it also has a genetic influence.
Teeth discoloration occurs regardless of brushing.
So I tried home care teeth whitening.
In fact, the effect is minimal and the usage process is cumbersome.
In the end, it's probably buried somewhere in the house.
To be honest, at the dentist I go to, my teeth are
Because it is so weak, teeth whitening is not recommended.
But these days, I'm thinking about getting it at least once!
If you happen to get teeth whitening done on your teeth
How many times do I need to take it to see any results?ㅜㅜ