In a post celebrating daughter Rya Rose, 11 months, and her recent milestones, the Teen Mom OG star admitted that these moments with the infant are bittersweet as Rya is their last baby.
"Our happy girl ❤️ crawling a million miles and hour 😂, saying hi, and has a bunch of teeth 😩," Lowell wrote. "Few more weeks and she will be one!!! She's SUCH a happy & good baby! Can't believe it's our last 🥲🥲🥲"
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.
The couple, both 30, shared that their fourth baby girl would be their last while revealing her sex in February 2021.
"We have found out that we are going to be having a … drumroll please … another girl!" Lowell told Celebuzz at the time. "While we wanted a boy since this is our last, as long as she's healthy ... that's really all that matters. This is our last and final but we know one day we will have a grandson and adore him!"
While speaking with PEOPLE last October, Lowell shared her family has a "whole movie theme" going on when it comes to names.
"Novalee, her name came from a movie. And Vaeda's name is from a movie as well, My Girl. And then one time we were watching the new Disney movie with our girls, Raya and the Last Dragon, and I was telling Tyler, 'Wow, isn't that a really pretty name? Like Raya is a super pretty name,' " she recalled.
"So with the whole movie theme that we kind of have going on, we were like, 'Oh my gosh,' like we really ended up falling in love with the name Raya," she explained.
As for Rya's middle name, Rose, Lowell said her daughter Nova was in charge of picking the second moniker.
"She got to give her sister her middle name, which she was all excited about. And then we were just like, 'Cool. Rya Rose, it's really pretty,' " she said.