The star of US drama Suits told Vanity Fair the pair are enjoying "special" time together.
"We're two people who are really happy and in love," the 36-year-old said.
Markle revealed she and the prince had been in a relationship for six months before the rest of the world found out at the end of 2016.
There was a media frenzy when it was revealed Harry was dating the US star, the pair having met in July last year.
The intense interest prompted the prince to issue a statement, attacking the press for subjecting his girlfriend to a "wave of abuse and harassment".
'This is our time'
She admitted to Vanity Fair that the situation "has its challenges" and "comes in waves", and that "some days it can feel more challenging than others".
"Right out of the gate it was surprising the way things changed," said Markle, who plays lawyer Rachel Zane in the TV drama.
"But I still have this support system all around me, and, of course, my boyfriend's support."
She says she doesn't read any articles about her - either about her private life or her work.
"I haven't even read press for Suits. The people who are close to me anchor me in knowing who I am. The rest is noise."
Asked how she handles tabloid speculation about herself and Harry, Markle said: "We were very quietly dating for about six months before it became news, and I was working during that whole time, and the only thing that changed was people's perception.
"Nothing about me changed. I'm still the same person that I am, and I've never defined myself by my relationship."
She's aware however, that as the relationship progresses, the spotlight might turn more on to her and the prince.
"We're a couple," she said. "We're in love. I'm sure there will be a time when we will have to come forward and present ourselves and have stories to tell, but I hope what people will understand is that this is our time.
"This is for us. It's part of what makes it so special, that it's just ours. But we're happy. Personally, I love a great love story."