Can a Brazilian citizen living legally in the UK with an Eur

[ObliviousPenguin01]

Hi, I've been allowed to stay in the UK through my Mom whom was married to an European citizen (Portugal) for over 9 years. I moved to the UK while still a minor (16 years old). I currently work in the health care department, pay my taxes and have zero criminal record so I was wondering whether I'm eligible for UK citizenship. At the moment I possess a visa titled "residence card of a family member of an EEA national" which will expire in 2020. Although my mother has since divorced from said European citizen my visa remains active as far as I can tell due to the fact that I've recently traveled outside of the UK and back in with it without any problems with the use of that same visa. I appreciate any help that I can get on this matter and will provide any further information that may be required.

[secret.simon]

When did your mother marry the EEA citizen and when did they divorce (issuance of divorce absolute)? Dates in month/year please.
Which year did you arrive in the UK? How old are you now? Have you been away from the UK for any period exceeding six months in the year?

[ObliviousPenguin01]

Thank you for your quick response. My mother married him in November 2007 whereas the divorce was finalized in April of 2015. I arrived in the UK in 2007 when I was 14 years old. I am now about to turn 24 this year. I have not been away from the UK for longer than six months since my arrival back in 2007.

[secret.simon]

Assuming that you are on friendly terms with your former EEA step-parent, you should be able to apply for PR Card, by submitting
a) Proof that he was exercising treaty right in the UK or already held PR himself between 2007 and 2015; and
b) Proof of your age and relationship to his spouse (birth certificate and your mother's marriage certificate) at the time.

[ObliviousPenguin01]

Okay, and in the worst case scenario that we are no longer on friendly terms, is there any other option? Can it be done without him?