“I don’t have many friends, because of who I am,” Brown reveals. “I didn’t go to school, so I don’t have the best social skills when it comes to people my own age and friendships. I struggle with that quite a bit. I missed out on a few things. But I’m working through them.”

Millie Bobby Brown celebrated her 21st birthday on Wednesday, Feb. 19, and shared a glimpse into how she spent the day, sharing a video of herself sporting platinum blonde fishtail braids and a green bustier as she blew out a candle on a heart-shaped cake.

Millie Bobby Brown was only 11 years old when most of her fans met her in the first season of Stranger Things –– but the actress is not so little anymore as she just celebrated her 21st birthday.