Billie Lourd Shares Sadness That Late Mom Carrie Fisher Won't Experience 'Magic' of Grandchildren

Barry King/WireImage Carrie Fisher and Billie Lourd in 2015

Billie Lourd is opening up about balancing her grief for her mom with the joy of being a mom herself.

Reflecting on the sixth anniversary of Carrie Fisher's passing on Tuesday, the Ticket to Paradise actress talked about her feelings on the difficult day, which comes just two weeks after welcoming daughter Jackson Joanne.

Lourd and husband Austen Rydell, both 30, are also parents to 2-year-old son Kingston Fisher.

"✨❤️✨It has been 6 years since my Momby died (feels like 2 but also like 705 at the same time?). And unlike most other years since she's died, this year, these past two weeks have been some of the most joyful of my life," Lourd wrote.

"Giving birth to my daughter and watching my son meet her have been two of the most magical moments I have ever experienced. But with the magic of life tends to come the reality of grief," she continued. "My mom is not here to meet either of them and isn't here to experience any of the magic."

Lourd admitted that "sometimes the magical moments can also be the hardest."

Never miss a story — sign up for PEOPLE's free daily newsletter to stay up-to-date on the best of what PEOPLE has to offer, from juicy celebrity news to compelling human interest stories.

RELATED: Pregnant Billie Lourd Wishes Mom Carrie Fisher Filmed While Expecting: 'Would've Been Incredible'

"That's the thing about grief. I wish my Momby were here, but she isn't," Lourd continued, going on to discuss the ways she keeps Fisher's memory alive for her little ones.

"So all I can do is hold onto the magic harder, hug my kids a little tighter. Tell them a story about her. Share her favorite things with them. Tell them how much she would have loved them," Lourd shared.

"For anyone out there experiencing the reality of grief alongside the magic of life, I see you. You are not alone," the mom of two concluded. "Don't ignore either. Life can be magical and griefy at the same time."

The actress's father, Bryan Lourd, first revealed news of his granddaughter's birth Tuesday while speaking at Variety's Dealmakers Breakfast in Beverly Hills, California.

"My daughter had a baby last night," he said while sitting down with Claudia Eller, Variety's chief production officer. "I left the hospital at 1:30 and got there this morning at 6. I'm a little tired, but happy."

"Everything's great," he added. "So if I wander, it's because the adrenaline is still flowing."

Lourd first revealed her baby bump in September at the London premiere of Ticket to Paradise, posing with her hands on her belly alongside Rydell.