We appreciate your keenness and your efforts to seek advice. We ask Allaah to make things easy for you and to give you a way out.
Women are commanded to conceal their adornment from strange men who are not their mahrams, because Allaah says (interpretation of the meaning):
“And tell the believing women to lower their gaze (from looking at forbidden things), and protect their private parts (from illegal sexual acts) and not to show off their adornment except only that which is apparent (like both eyes for necessity to see the way, or outer palms of hands or one eye or dress like veil, gloves, headcover, apron), and to draw their veils all over Juyoobihinna (i.e. their bodies, faces, necks and bosoms) and not to reveal their adornment except to their husbands, or their fathers, or their husband’s fathers, or their sons, or their husband’s sons, or their brothers or their brother’s sons, or their sister’s sons, or their (Muslim) women (i.e. their sisters in Islam), or the (female) slaves whom their right hands possess, or old male servants who lack vigour, or small children who have no sense of feminine sex. And let them not stamp their feet so as to reveal what they hide of their adornment. And all of you beg Allaah to forgive you all, O believers, that you may be successful”
Hence it is required that the clothes with which a woman covers herself should not be an adornment in themselves, because she is commanded to conceal her adornment as stated above.
It is also essential that the clothing be wide and loose so that it covers all the body, and it should be thick so that it is not see-through.
You should advise your family and explain to them the necessity of adhering to that which Allaah has prescribed and enjoined. Explain that to your husband also, for he is responsible before Allaah and is required to protect you and have protective jealousy concerning you.
Ask Allaah to protect you and to guide your family to that which is good; remain steadfast in what you are doing even if that makes them angry and upset. For there is no obedience to any created being if it involves disobedience towards the Creator, and it is not permissible for you to obey your parents or husband in wearing that which Allaah has forbidden, or neglecting to do something that Allaah has enjoined, either at your wedding or afterwards.
The Prophet (peace and blessings of Allaah be upon him) said: “There is no obedience if it involves sin, rather obedience is with regard to that which is good and proper.” Narrated by al-Bukhaari, 7257; Muslim, 1840.
See also questions no. 11967, 6408, 6991, 5393; these questions explain the ruling on hijab and the description of hijab. You should read them and choose whatever is appropriate to show to your parents so that they will be convinced of the shar’i ruling.
We ask Allaah to make you steadfast until death. And Allaah knows best.