For Teen Mom star Maci Bookout, co-parenting son Bentley with ex-fiance Ryan Edwards is no picnic.

"We barely speak," Bookout, 19, admits in the new issue of Us Weekly. "But I don't think it's a bad thing. We just try to avoid arguments as much as possible."

But argue they do: the former couple have sparred over everything from child support to his new girlfriend to pacifiers. On one episode of MTV's reality hit, Bookout struggled to wean Bentley, 22 months, off of his pacifier -- only to have dad Edwards, 22, give in to their son's demands.

"He's just going to get [his pacifier] at Ryan's house," Bookout tells Us. "I think Ryan spoils Bentley and really has no boundaries as far as discipline. With me, I don't want Bentley to grow up and be a brat when he's 4 years old."

The Chattanooga State journalism student and waitress adds that her ex isn't much of a hands-on dad during Bentley's visits to his home. "As far as Bentley getting fed, his diaper changed, taking a bath, it's mainly Ryan's mom doing all of that," Bookout says.

She adds hopefully that Edwards' new girlfiend could "make Ryan want to grow as a father. I don't want him to find a girlfriend who just wants to party."

Meanwhile, Bentley has a new father figure in Kyle King, Bookout's beau of six months. "It's weird to see [Bentley] loves Kyle enough that Kyle can make him feel better...I like that emotional support that comes with having a partner," Bookout cooes of King, 22.

Wedding bells for childhood pals Bookout and King? "We're going to see what happens," she tells Us.

For more of our exclusive interview with Maci -- plus sitdowns with Farrah, Amber and Catelynn -- pick up the new issue of Us Weekly, on stands now!