The engaged couple welcomed daughter Novalee Reign on Jan. 1
Credit: Jesse Grant/Getty

It’s been more than five years since Catelynn Lowell and Tyler Baltierra first appeared on MTV’s 16 and Pregnant, but the newly engaged couple – who just welcomed 3-month-old daughter Novalee Reign – is back for a brand new season of the hit reality show’s spin-off series Teen Mom.

“It’s kind of crazy,” Lowell tells PEOPLE of returning to the network that first documented the high school sweethearts’ deeply personal story of putting daughter Carly, now 5, up for adoption.

“We still can’t watch when we were saying goodbye to her,” she says. “We both end up bawling and just can’t even go there.”

But as painful as it is for the couple to revisit the tough time, when it came to making the decision to sign on for another series, they didn’t have any hesitations.

“We do it to educate about adoption,” says Lowell. “So we were all for sharing our story. And people will see that in the show too – us navigating our relationship with [Carly’s adoptive parents] Brandon and Teresa, how Nova comes into play, all that kind of stuff.”

In the new series, which premieres Monday, cameras follow Lowell throughout her second pregnancy and the birth of the couple’s daughter.

“We’re adjusting,” she says of motherhood. “It hit me after a while of having her home because I’d seen the other girls being moms, but this is the first time I’m actually parenting a child. It’s totally different from what you expect.”

But that isn’t the only thing keeping the new parents busy. They’re also planning to tie the knot Aug. 22 in Michigan.

We’re really looking forward to it,” she says. “It’s kind of like an old regal masquerade type theme, and we’ll have king throne chairs and lots of reds, golds and whites.”

Teen Mom OG premieres Monday at 10 p.m. ET on MTV.

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