"I absolutely love being a mother," Castle-Hughes, 19, told PEOPLE at the Toronto International Film Festival premiere of her new movie The Vintner's Luck. "It's been a blessing. It's fun and it's hard, but it's absolutely amazing."
At the age of 17, Castle-Hughes gave birth to Felicity-Amore, now 2, with boyfriend Bradley Hull. Since then, she's chosen to be out of the Hollywood spotlight to focus on taking care of her toddler, who is blossoming into a mini version of herself.
"Felicity's just like me. All trapped into a little body," says Castle-Hughes. "It's quite full on. She's got lots of energy and quite dramatic. She's picked up quite a few dramatic tendencies from me, which is good and bad. But it's very exciting to watch her personality develop."
Preparing for ParenthoodAs for being a teenage mom, the youngest female star ever to be nominated for a Best Actress Academy Award – she was 13 – says, "It's no different for me than any other mum in the world. It can be a little stressful and tiring, but it's the most rewarding thing."
While critics called her too young to become a mother, Castle-Hughes said she respectfully disagrees. "I was in a very different situation when I had her. I was in a loving and stable relationship with her father, who I'm still with. I had quite an established career and so the decision to have her was very easy," she says.
"Once I found out I was pregnant there was no decision really. I was shocked but it was just like, 'Okay, we are having a baby. That's great.'"
She adds, "I've lived a fast-paced life, but I had the best childhood. I didn't miss out on anything by having my daughter at a young age ... If I would go back and change things, I would not. I can't imagine living my life without her."
Extended EngagementCastle-Hughes is still in a happy and committed relationship – and revealed that she and Hull, 22, have "been engaged for 2½ years," she said enthusiastically. "It's a very long engagement but no immediate plans. Eventually it will happen. I love him and we will be together for the rest of our lives."
As for Hull's parenting skills, Castle-Hughes says Felicity-Amore could not have a better dad. "He's very present in her life. He's a fantastic father who absolutely loves her. He's very gentle and very loving with her. He does everything with her and is the perfect dad."
Expanding the FamilyThe New Zealand native also says she "absolutely" wants little Felicity to have siblings. "I have no idea how many, but it changes every day. I come from a big family, so I'd like to have a big family."
Castle-Hughes says she has a difficult time being away from her daughter. "When I'm away from her it's torture. The minute I see a little kid on the street, I want to be with them. The [parents] go, 'Excuse me, can you not touch my child?' And I'm like, 'I just wanted to hold them because I miss my own kid!'"