Speaking to the TV Times, the Zainab Masood actress recalled being told by Norwood that she had worked on the show for a fifth of its history.
She explained: "I think it was Ricky Norwood, who plays Fatboy, who then said to me, 'You know, you've been in EastEnders for a fifth of its life', and that frightened me a bit.
"Not in a bad way; it just made me think that I've created this person that I hope people have liked, and maybe it's time to go off and do it elsewhere."
The 44-year-old also shared details of the moment she told on-screen husband Nitin Ganatra of her plans to quit, which she made official in December.
"It was really quite horrible," she recalled. "He sat in the dressing room and I said, 'Listen up; I've got some news'. Marc Elliott and myself used to play tricks on people the entire time so, when I went all serious, Nitin was like, 'This is a joke, right?' and I went, 'No, I'm not going to tell you a joke. I'm leaving'.
"He went, 'Very funny, now, come on, we've got to go on set', and I was like, 'No, Nitin, this is not a joke'."
"He went very quiet, but then I explained my reasons and he understood," the actress added. "The same goes with Himesh [Patel, who plays Tamwar]. He was particularly upset."
Wadia also divulged that producers had originally planned for her character to replace the legendary Pauline Fowler, adding: "I said as long as it's a Pauline Fowler who has a sense of humour, I'm happy to play her.
"That's what I wanted to make very clear; that I wanted her to be funny, and they were happy with that because they'd known me for my comedy work."