Billie Lourd reflects on grief as she marks Carrie Fisher's birthday

Billie Lourd has honoured her late mother, Carrie Fisher, on what would have been her 70th birthday.

Taking to Instagram on Wednesday, the American Horror Story actress shared a throwback photo of her mum celebrating her birthday.

In the accompanying caption, Billie admitted she continues to grapple with Carrie's sudden passing. The Star Wars actress died at the age of 60 in December 2016 after suffering a heart issue on a flight. Carrie's mother, Hollywood icon Debbie Reynolds, passed away the following day at the age of 84.

"Today would have been my Momby's 70th birthday. Which feels way too young an age to be dead for almost 10 years," she began. "She should have been alive for at least 10 more years - not dead for 10. The last birthday I got to celebrate with her was her 60th. I wish I would've known it was her last but you never know a last is a last."

Billie went on to describe how she "woke up feeling really angry" that Carrie "wasn't able to get sober".

The Postcards from the Edge author had been open about her experiences with bipolar disorder and drug addiction over the course of her life.

Accordingly, the Ticket to Paradise star explained that she tries to give herself space to "let that anger sit for a moment".

"The next feeling that showed up to the emotional party was a guest who is sure to show up every year - my girl Sadness. She always tends to be hiding right behind her old friend Anger," the 34-year-old continued. "Being with my momby when she was at her best felt like home. A warm hug you never want to pull away from."

Elsewhere in the heartfelt message, Billie noted that she wished Carrie could have met her own children, Kingston, six, and Jackson, three, whom she shares with husband Austen Rydell.

"(I) feel so lucky to be able to Carrie on my version (of) that Carrie cozy (sic). It wouldn't exist if she didn't exist. And I'm so beyond happy she existed," she stated, before offering words of support to those who are dealing with the loss of someone who had struggled with drug addiction. "May you allow all of the emotional guests to attend the emotional party - anger, sadness, frustration, joy, numbness, warmth, (insert emotion here). You are not alone."