Can I get British citizenship?

[saudiG]

Hi, I am a Malaysian citizen born in Malaysia (1980) to a Malaysian mother and Nigerian father. At the time of my birth, my mother was a Malaysian citizen but entitled to the UK Right of Abode (she was born in 1948 and Malaysia was a British Colony at the time of her birth). She was granted the UK Right of Abode in 1995 as she had previously worked and lived in the UK.

She was given British Citizenship in 1997 and was able to secure British citizenship for my 3 younger siblings who were born after Jan 1, 1983. However, as i was born in 1980, she was told that perhaps she could transfer the Right of abode to me.

I applied for the Right of Abode in 1997 (about 6months to my 18th birthday). My application was unsuccessful on the grounds that I was 18 years of age, my mother was not a British citizen at the time of my birth, neither maternal nor paternal grandparents were British citizens and I had previously not lived in the UK.

My question is whether I have any grounds at all to claim British citizenship as my mother, and younger siblings are British nationals. Also, my elder sister is currently living and working in the UK, having been granted the tier 1 visa (3yrs ago). My father applied for and was granted settlement to join my mother in the UK last year November, and was told he can apply for BC after 2yrs.
Could i get BC or the ROA, ILR or anything at all on compassionate or any other grounds??? I really, really would appreciate any help on this.
Thank you for your responses...