Today, the couple – who placed their baby, named Carly, with a North Carolina couple – say they have no regrets about their choice.
"We're not the right parents for her now," Catelyn, 18, tells PEOPLE in this week's cover story. Adds Tyler, also 18: "She deserves so much better."
Still, Catelynn and Tyler – who are now engaged and currently appearing on the MTV spinoff Teen Mom – both acknowledge that the past year has been emotionally challenging.
"When I see a dad and a little girl walking to the park, I think, 'I wish I could do that right now,' " admits Tyler, who has a tattoo of Carly's name, newborn handprint and birthdate.
Notes Catelynn: "There's not a day she doesn't pass my mind. I want to make her proud."
For much more with Catelynn and Tyler – as well as updates and exclusive photos of the other Teen Mom stars and their babies – pick up this week's new issue of PEOPLE, on newsstands Friday