Meghan said designer Clare Waight Keller respected her vision for the dress, from the shape of the neckline to the length of the sleeves - and recognised the importance of tailoring as the outfit had to be “modest”.
The couple realised the day would be what Harry called a “global wedding”, but featuring personal choices would make it more “intimate,” said Meghan.
The bridal gown is the star attraction of a new Windsor Castle exhibition about the royal wedding, which includes audio commentary recorded for visitors by the duke and duchess.
Touching stories behind the couple’s big day are revealed, from Harry joking about joining the Queen and Meghan for a meeting to choose a tiara, to how a cold Easter meant there were less flowers to pick for his wife’s wedding bouquet.
Meghan says in the commentary: “I had a very clear vision of what I wanted for the day, and what I wanted the dress to look like, and so what was amazing in working with Clare is that sometimes you’ll find designers try to push you in a different direction.
“But she just completely respected what I wanted to see for the day, and she wanted to bring that to life for me.
“So I knew at the onset I wanted a bateau neckline, I wanted a cropped sleeve, I wanted a very timeless, classic feeling and, obviously with respect to the environment we were in and St George’s Chapel, being really modest in what it would look like, I knew that the tailoring was so key, because the dress itself would be so covered up.”
Meghan says in the commentary she had followed Clare Waight Keller’s career for a long time and she ticked “all the boxes” from being British, to reflect the duchess’ new home, and a woman, to working for Givenchy as artistic director, a global fashion house which added an international dimension to the big day.
The gown and the five-metre long silk tulle veil - embroidered with flowers from each of the 53 Commonwealth nations - were created after 3,900 hours of work by a 50-strong team.
The dress’ luminosity is down to the double-bonded silk cady - fabric woven on both sides of the loom - which catches the light.
Speaking in the commentary Meghan adds: “There was a great level of detail that went into the planning of our wedding day.
“I think for us, we knew how large the scale of the event would be, so in making choices that were really personal and meaningful, it could make the whole experience feel intimate, even though it was a very big wedding.”
On her wedding day, Meghan wore Queen Mary’s diamond and platinum bandeau tiara, lent to the duchess by the Queen, which is part of the exhibition.
The duchess described her visit to the head of state to choose a headpiece as “an incredibly surreal day”.
The duke, who joined Meghan for the visit to the Queen, joked in the commentary: “Every girl’s dream to be able to try on a tiara, and, funnily enough, the one that suited the best, the one that looked the best on you without question, I shouldn’t have really even been there, but such an incredible loan by my grandmother, it was very sweet.”
The bride’s bouquet, which featured a number of plants and flowers including sweet peas and sprigs of myrtle, was designed by florist Philippa Craddock and has been recreated using artificial silk flowers for the exhibition which opens on Friday.
The duke and duchess said cold weather earlier in the year meant there were less flowers available for the wedding bouquet from their cottage garden at Kensington Palace.
Meghan revealed they had been doing some planting in the “fall” and said the duke made a “really beautiful” gesture by picking blooms for her on their wedding day - May 19.
Harry added: “We didn’t have as many flowers in our little garden as we had hoped for because I think it snowed at Easter.
“That kind of ruined the whole thing. But, they’re very much a bouquet of wild flower, wild flower meadows and making sure that we had forget-me-nots in as it was one of my mother’s favourite flowers...”
The duke’s Household Cavalry frockcoat made for the wedding is not available for the exhibition but another identical one owned by Harry has been loaned for the display
Also on display are the wedding outfits worn by pageboy Prince George, a miniature version of Harry’s coat, and bridesmaid Princess Charlotte, an ivory silk dress by Clare Waight Keller.
Harry joked: “We had 10 bridesmaids, page boys under the age of seven which everybody says is impossible to have them behaving, but they did it.”
Meghan quipped: “It was a miracle.”
A Royal Wedding: The Duke and Duchess of Sussex at Windsor Castle runs from October 26 to January 6 at Windsor Castle.