"I like to be spontaneous and live in the moment," the model and star of Paper Towns, in theaters Friday, tells PEOPLE in the magazine's latest issue.
And that way of thinking applies to Delevingne's take on being openly bisexual, as well.
"I haven't made a concrete decision about anything," says the actress, who is currently dating model-actress St. Vincent and took her along to the Paper Towns premiere Tuesday in New York City. "Every day, I change. Every day, I'm discovering new things about myself."
One thing Delevingne doesn't plan on changing is her willingness to be open about her sexual orientation.
"I want to be as open with people as possible," she says. "There are a lot of things people don't know about me, but I just want to be honest."
For more from the Paper Towns star, pick up the latest issue of PEOPLE, on newsstands Friday