I'm a revert and live in a non-Muslim country, my family consists of non-Muslims, too. Furthermore, I'm attending university and live in the dorm, where I have three non-Muslim roommates. For a Muslima it is not permissible to not wear hijaab while being surrounded only be women (who are non-Muslims)?

It is permissible for a Muslim woman to remove her hijab in the presence of other women whether or not they are Muslims so long as they are trustworthy not disclose her physical features to men.