Do you have any brothers or sisters?
Your browser is out of date. To view the videos, please update your browser
Unfortunately I don't have a brother, but I have got two sisters.
I don't have a brother.
The change I would make is to the second half of your sentence - "but I do have two sisters." Depending on location in the English-speaking world and the formality of the circumstances, any of these forms (including your original) would be fine.