Ms Markle's parents, Thomas Markle and Doria Ragland, said their daughter was a "kind and loving person" and they were "incredibly happy".
"Any the end of day I'm really just proud of who I am and where I come from and we have never put any focus on that", she said in the BBC interview.
The pair were introduced in July 2016 by mutual friends in London, Markle confirmed in September. Just under half a mile away from Buckingham Palace, Westminster Abbey hosted the wedding of Queen Elizabeth II in 1947 and Prince William and Kate Middleton's nuptials in 2011.
The Duke and Duchess of Cambridge cheered the engagement.
"Meghan has an effortlessly chic sense of style, which we've always admired", said Line president and co-founder John Muscat.
Rumours of their relationship immediately set off a frenzy of media speculation and were confirmed when Kensington Palace issued an unprecedented statement in November previous year condemning the "wave of abuse and harassment" directed at "his girlfriend".
Prince Harry said his mother would have been "over the moon, jumping up and down" at the engagement and "best friends with Meghan". The iconic domed landmark housed the wedding of Prince Harry's parents Charles, Prince of Wales, and Diana Frances Spencer in 1981.
She attended a private primary school before studying at a girls' Roman Catholic college and later graduating from Northwestern University School of Communication in 2003, just as her acting career was beginning.
There is a long-running custom barring royals from marrying Catholics and divorcees.
Forgoing royal family history, Prince Harry may opt for a more intimate venue, unique to him and his fiancé.
Until recently, a union with Ms Markle would have ruled Prince Harry out of succeeding to the throne - due to her being a Roman Catholic.
"We're a couple. We're in love", she said in the interview. It's part of what makes it so special, that it's just ours. "We know this particular coat is one of her favorite pieces so we have officially made a decision to name it the 'Meghan'".
In September, UsWeekly reported that a source said that Markle had met the Queen and "it went well".
Markle's engagement ring features diamonds from Diana's collection.