Ellen Page probably would have come out at some stage – "I felt my career and my work were suffering from me being closeted," she says – but making Freeheld, a true story about a lesbian couple's fight for equality, sealed the deal.

She'd been involved in the project – adapted from the Oscar-winning 2007 short documentary of the same name – for about six years, but as production edged nearer she began to feel it was "just wildly inappropriate" to play one of these crusading women while still hiding her own sexuality.

"It was pretty crazy how much my own journey paralleled the development of the film," she says. "I'm sure part of my decision to come out was about realising you could not be closeted and play that role. But it was ultimately about my personal wellbeing, quite frankly. Very selfish on my part."

Well, not so selfish, really. Since grabbing headlines by announcing she was gay on Valentine's Day 2014 – on the podium at the inaugural Time to Thrive gay rights conference – the 28-year-old Canadian actor-producer who hit the mainstream with her starring turn in 2007's Juno (and has since joined the X-Men franchise as Kitty Pryde) has become a cult hero of sorts.

She gets it, but Page admits she's a bit uncomfortable about it, too.

"I've got a lot of luck in my life, and there are so many members of the LGBT community who are so much more vulnerable than me," she says. "For me, coming out felt like a moral imperative. I felt guilty for not being out – and quite frankly, I think I should have felt guilty."

Contrasting her own good fortune with how tough others have it, she says, "made me go: 'Hey Ellen, dude, you're privileged, you have a family that loves you. Just tell people you're gay'."

In Freeheld, Page plays Stacie Andree, a young auto-mechanic whose partner, Laurel Hester (Moore), is a police detective in Ocean County, New Jersey. They meet, fall in love, buy a house together and bicker about whether or not Stacie can get a dog. All the while, Laurel keeps her relationship secret.

When her partner on the force (Michael Shannon) visits, she introduces Stacie as her "room mate". Stacie is devastated.

"It is painful to her, and I think it's something a lot of people in the community can relate to," Page says of Stacie's status as a dirty secret. "It's good for people to see what that dynamic is like in a relationship. It's not a nice way to live – and no one should have to, you know."

The closet door is blown open when Laurel is diagnosed with terminal cancer. She wants her police pension to go to Stacie, but the county officials (known as freeholders, hence the title) won't allow it. Battle lines are drawn.

In Page's eyes, it's people like Andree and Hester who are the real heroes of the gay rights movement. She classes their story, as told via Cynthia Wade's documentary, alongside a couple of other docs, on Pussy Riot and gay-rights campaigners in Uganda ("they are literally risking their lives every day just by being who they are and speaking out against terrible brutality") as inspirations in her decision to come out.

Rupert Everett and Richard Chamberlain are among the few male actors to have come out, and both have advised against it, saying it's a career killer. But Page has nothing but good things to say about her experiences so far.

Watching the video of Page's coming out speech, you can almost see the sense of relief as she says the words "I am gay". Is that how it felt?

"Maybe it sounds over the top but it really did feel like every cell in my body changed, I felt like I changed physically, my energy levels changed, and I've continued to feel that," she says.

Professionally, she says she's feeling more inspired than ever before. She's working on a couple of projects where she plays gay women – one of them opposite Kate Mara, with whom she made a short comedy piece for Funny or Die, a True Detective parody called Tiny Detectives – but she's still being offered straight roles too.

Things are changing, of that she's certain. The push for diversity on screen and behind the camera is gathering momentum, "and it's really, really exciting".

Do you think that if we talk again five years from now the whole issue of your sexuality will be a total non-issue?

"In five years? Huh. I certainly, certainly, certainly hope so," she says.

For younger people, sexuality is not such a big deal, she thinks, "and as we move along in time that's what we're going to see in society".

Maybe it will take a little more than five years, but she hopes for a time when no one bats an eyelid at seeing a same-sex celebrity couple walk down the red carpet on opening night or at the Oscars.

"How awesome will it be," she adds, "when there's a time when a young actress doesn't feel like she has to make a speech to come out."

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