Billie Lourd shared a heartfelt message about experiencing grief and joy

Carrie Fisher's force lives on in Bille Lourd.

On the sixth anniversary of her mom's death Dec. 27, Billie reflected on what it's like to navigate life without her.

"It has been 6 years since my Momby died (feels like 2 but also like 705 at the same time?)," the mom of Kingston, 2, and Jackson, 2 weeks, wrote on Instagram alongside a photo from her childhood.

"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. Giving birth to my daughter and watching my son meet her have been two of the most magical moments I have ever experienced."

While Billie relishes in being a mom, she admitted that "sometimes the magical moments can also be the hardest," without her own around.

"With the magic of life tends to come the reality of grief," she wrote. "My mom is not here to meet either of them and isn't here to experience any of the magic. That's the thing about grief. I wish my Momby were here, but she isn't."