What of English speaking South Africans (descended from British settlers)? What was their standing during apartheid?
If your character was 11 in the early 90s, there was a less pronounced difference between English vs Afrikaner than earlier in history. They would have been treated much the same as those of Afrikaner descent.
All English speakers would have been taught Afrikaans at school, even though English was the language of commerce.
The Democratic Party in South Africa was largely anti-apartheid. They were heavily made up of those of English descent, but also appealed to younger Afrikaners. Of course, you also had English descendants who were part of the National Party (largely pro-apartheid). Interesting note, but the DP is now the Democratic Alliance (DA), and they are now the largest opposition party to the ANC (African National Congress, Nelson Mandela's party).
Those of English descent tended to be more liberal, both in terms of religion, and social policies. Remember, South Africa under the National Party was highly conservative, and church and state were highly intertwined. The English were more likely to be Methodist, vs. the much stricter 'three sister' churches of the Afrikaners, like the Dutch Reformed church.
I lived in SA (Cape Town) for around 7 years. Beautiful place with quite a complicated history. If you have any specific questions about growing up in SA, I can forward them to my South African friends. I don't always peek in here, but feel free to PM.
My two cents...if you intend to write about South Africans, it is worth understanding historical events from multiple perspectives. My experience in that country taught me that history depends very much on who is telling it!
Hope this helps.