"I'm sure you'll feel better and better as you are gradually settling in." or yo'u could write I'm sure you will feel better as each day passes by and you get settled in your new place.

There is nothing wrong with your sentence. The only complaint one might give voice to is that it is, maybe, a bit awkward. But to be sure, I'd have to see the context. If you feel like you want to use your own words, here is a rewrite: As long as you are gradually settling in, I am sure you will feel better and better.

Ok I got it..thank you very much, very useful..:)