Since Catelynn bid farewell to "Teen Mom" nearly two years ago, the 23-year-old's life has changed considerably: She and fiancé Tyler are planning their upcoming nuptials, and they joyfully welcomed daughter Novalee Reign last month. Before the beloved docu-series -- featuring all the original cast members -- makes its highly anticipated return on March 23, we're selecting key moments from each season of Cate's MTV journey, appropriately beginning with "16 and Pregnant" and ending with the fourth season of "TM":
Saying goodbye to Carly, from "16 and Pregnant"
Before welcoming their little girl, the pair outlined an adoption plan and worked with a counselor to find a stable home environment for their child. Shortly after they heard Carly's screams in the delivery room, a crying Ty told Cate "we can do this -- this is all for her." A few days later, they tearfully embraced the newborn -- as well as Carly's legal parents Brandon and Theresa, featured in the clip above -- and said a temporary farewell to the trio until their next visit.
Introducing the future Mr. and Mrs. Baltierra, from "Teen Mom: Season 1"
Cate's longtime love choked up as he poured his heart out to his then-girlfriend during a formal dinner date -- which eventually turned into their engagement. He stated how much they had endured together and eventually confessed, "I want you to be mine forever — I want you to grow old with me." Cate enthusiastically said "yes" to her beau's heartfelt proposal -- and they sealed the very happy occasion with lots of hugs and kisses.
An emotional reunion with Carly, from "Teen Mom: Season 2"
Approximately one year after "16 and Pregnant," Cate and Ty excitedly traveled to West Virginia to see their biological daughter and her legal parents. The happy excursion in the park featured lots of smiles and joy -- and is widely regarded as one of the most unforgettable incidents in the show's history
Facing body image issues, from "Teen Mom: Season 3"
The sweethearts faced a major relationship hurdle when Catelynn expressed that she was feeling insecure about her physical appearance -- and her negative feelings were only heightened when Ty expressed an interest in going clubbing. Fortunately, the two were able to maturely express themselves during a joint therapy session and emerge from the tough spot with a clearer understanding of one another.
High school graduation, from "Teen Mom: Season 4"
It was an especially proud moment for the duo as they donned their caps and gowns, and received their diplomas in front of their loved ones. Before they closed the chapter on that significant part of their education, they couldn't help but reflect on how far they'd come since Carly's birth.
+ Which do you think is Catelynn's most memorable experience? Share your thoughts below, and keep checking MTV News for more "Teen Mom OG" coverage -- including a look at Maci's, Amber's and Farrah's unforgettable moments. And be sure to catch the show's premiere on Monday, March 23 at 10/9c!