Constance Wu is all alone. It’s two weeks before Crazy Rich Asians will premiere in the US and become an instant hit and the most talked-about film of the summer (a sequel has already been announced). The halls of the Beverly Wilshire are abuzz with studio staffers. But here in this suite, it is just Wu and the weight of expectations from an entire generation of Asian Americans yearning to be seen.

“It’s really lonely,” says Wu as she perches cross-legged on a sofa in white and red Oscar de la Renta, her stiletto heels abandoned on the floor. “In terms of a blueprint, a model, of doing what I’m trying to do … I don’t have that. I get really scared.”

It is a startling admission, because it is almost impossible to imagine Wu succumbing to that fear. Even before Crazy Rich Asians, the 36-year-old actor had already served as the linchpin for a make-it-or-break-it project for Asian American representation in Hollywood in 2015’s Fresh Off the Boat, in which she turned a “Tiger Mom”-style role into a surprisingly tender portrayal of an immigrant striver. The show, now filming its fifth season, is only the second Asian American family sitcom ever produced, and it came more than 20 years after the first, Margaret Cho’s All-American Girl, was cancelled after one season.

With Crazy Rich Asians, Wu is breaking an even longer dry spell. The film is the first to tell a contemporary Asian story with Asian American lead actors since The Joy Luck Club in 1993. Wu serves the crucial dual role of romantic lead and audience surrogate, a relatable American leading us on a journey into the heart of opulence, as academic Rachel Chu, who goes to meet her boyfriend’s parents, only to discover that they are the biggest property developers in Singapore – and have very specific ideas about the kind of woman he should marry.

Despite her precarious position in a very white entertainment industry, Wu has never given in to the pressure to remain apolitical. (“The ones who do that, I don’t let them represent me any more,” she says of agents and managers who want her to pipe down.)

Watch the trailer for Crazy Rich Asians

So when Paramount reportedly used CGI to make Ghost in the Shell star Scarlett Johansson “look more Asian”, Wu compared it to “the practice of blackface”. When Matt Damon was cast in the starring role in the Chinese mega-film The Great Wall, she lambasted the industry for “perpetuating the racist myth that … only a white man can save the world”. And when Casey Affleck was nominated for an Oscar in 2017, after allegations of sexual misconduct on the set of I’m Still Here, she unleashed a string of angrily sarcastic tweets about “the industry’s gross and often hidden mistreatment of women”.

Wu never planned to become a spokeswoman for Asian American frustration. “I don’t think anything through,” she admits. “I am very impulsive and reactive. I have always been a person who is kind of outspoken, but nobody knew who I was before. Now I have this weird thing called fame, and I wasn’t looking for it, I didn’t ask for it, but if you have it, you might as well use it for something good. And the best thing I think I can do is help amplify the voices of people who don’t feel heard.”

In other interviews, Wu has cited Pulitzer prize-winning author Viet Thanh Nguyen’s theory of “narrative plenitude” to explain the importance of diverse of representation in culture, but with me, she invokes a less lofty source – a famously benevolent American children’s TV star. “I think half or almost all of the pain in the world is people not feeling heard, people not feeling seen,” she says. “It’s like Mr Rogers, my hero, says: everything in the world revolves around love or the lack of it.”

In fighting for Asian Americans to be seen, Wu doesn’t shy away from calling out injustice. She speaks with excitement of Sandra Oh’s recent Emmy nomination for Killing Eve, but also anger that Oh is the first woman of Asian descent to be nominated for a leading role. “I think that says something about who the culture thinks has a story that’s worth telling,” she says.

Her outspokenness has come at a cost. After calling out Affleck, “People got mad at me. I have lost a lot of parts because of that and I probably will never be a member of the Academy … But that’s OK.”

When I ask what it’s like to bump into the very stars that she has criticised, she laughs. “I love Scarlett Johansson,” she says. “I’m not blaming Scarlett. She isn’t out there like, ‘Let me go choose the part that’s going to make people mad the most.’ But the only way she’ll know that she’s doing that is if we begin a conversation and say, ‘It’s not your fault, but this is something that’s important to a population.’”

The benefits of talking about it are clearly on display in Crazy Rich Asians, a fun romantic comedy that nevertheless had me welling up within the first 15 minutes. A scene showing thirtysomethings drinking beer and eating street food wasn’t particularly heartstring-tugging in itself – though the pangs inspired by the director Jon M Chu’s gratuitous food-porn shots were real. It was just that I had never before sat in a crowded cinema watching Asian people perform something other than martial arts, surgery, tech support or massage therapy.

Wu as Rachel Chu in Crazy Rich Asians. Photograph: AP

The movie tells a story that is not just Asian, but Asian American. Chu immediately seems foreign to her boyfriend’s Chinese-Singaporean family when she offers that most American of greetings – an over-enthusiastic hug. Later, concerns of Asian authenticity play out in tense scenes such as the one in which four generations of a family sit around a table making dumplings.

The cast includes actors of Asian descent from all around the world. “We’re not a monolith,” Wu says. “I think the one thing that we all share is not being the dominant culture of the country that we grew up in, and that environmental factor affects identity and character.” Her voice rises. “And the fact that people don’t realise that is kind of ridiculous to me. It’s like, ‘Oh, you think I relate to the beautiful films that China makes simply because we have the same face? You think my culture is just how I look?’ There are so many things that go into identity.”

As for her feelings of authenticity, despite having struggled with the same accusations of being an “unrefined banana” (yellow on the outside, white on the inside) that her character faces, Wu seems confident in asserting both her Asianness and her Americanness. “I grew up in a predominantly white community, so there was no question I was Asian there, you know what I mean?” she laughs. “I’ve struggled with it more since being in the public eye. There are a lot of Americanised things that I do, you know, because I am American born and raised.”

Such as? “Like, I wear my shoes in my house,” she confesses. “People are like, ‘What!? You are such a bad Asian!’ And I’m like, ‘Guys, it’s part of the outfit.’”

• Crazy Rich Asians is released in the UK on 14 September