covering of the face

Assalamualaikum, I am not entirely convinced that the niqab is compulsory for I have heard otherwise from some sources including hadith. I would like to be sure that it is compulsory before i go against my father's will by wearing it. Among these sources is the hadith narrated by Aisha(ra) that Asma, the daughter of abu bakr, came to see the prophet (saw) wearing a thin dress. The prophet turned away and said to her, "oh Asma, when any woman reaches the age of puberty, she cannot reveal any part of her body except this and this." And he pointed to his hands and face. Abu Dawud and Tirmidhi And i heard from another source that there were some women in the prophet's(saw) lifetime who did not cover their faces yet he(saw) didn't say anything. I do not find some of dalail given for Niqab convincing of which are: "Oh Prophet SAW! Say to your wives, your daughters and the believing women that they should lower their jilbaabs unto them... (Surah Al-Ahzaab, verse 59) Muhammad ibn Seereen RA said : ‘Ubaidah As-Salmaani RA asked regarding the commentary of this verse, thus he covered his face and head but exposed his left eye. Ibn Abbas RA said : Allah has commanded the believing women that when they come out of their houses due to a necessity, they should cover their faces from top of their heads using their jilbaabs and only expose one eye. In the verse quoted above it does not specify to cover the face but many of the sahaba could have interpreted it to include the face because of piety. Why is it that many ulema have concluded that niqab is not obligatory including sheikh yusuf al qaradawi. This makes the whole matter very confusing. What should i do if my parent's are of this opinion and won't allow me to wear niqab? Jazakallah.