'Teen Mom OG' 's Amber Portwood on Life After Prison and Staying Sober

"It's never too late to try to get your life back and do something positive," the reality star tells PEOPLE

Photo: MGoetz/Splash News Online

After drug abuse and domestic violence charges landed her in jail for 17 months, Teen Mom OG star Amber Portwood is returning for a new season of MTV s reality series and determined to get her life back on track.

“I didn’t want people to have a bad taste in their mouth of things that happened in the past,” she tells PEOPLE. “I thought, ‘This is my chance, don’t blow it.’ ”

Portwood made the drastic decision to report to jail back in June 2012 rather attend a court mandated rehab program.

“The only thing I could see happening to me if I [hadn’t gone] to prison is I would have died,” she says. “I would have overdosed. When you’re an addict you know what your bottom is.”

So Portwood made the choice for herself and her daughter Leah to get sober.

“Obviously I’ve had some speed bumps,” she says. “But it’s never too late to try to get your life back and do something positive.”

So while in prison Portwood earned her G.E.D. and is now trying to decide between colleges.

“The whole time I was in there I worked my ass off,” she says. “There were hundreds of hours of drug addiction classes. I did extra classes, parenting and anger management and even started teaching. I put myself in there for a reason so I didn’t want to make it a waste.”

As for her volatile relationship with ex Gary Shirley – who has another child on the way with his current girlfriend – the Indiana native says she’s moved on.

“We’re co-parenting the best that we can,” she says. “It’s not perfect and he still gets on my nerves, but we’re happy with the people we’re with.

For Portwood, that person is 43-year-old fiancé Matt Baier.

“He’s amazing, funny, caring, and loving,” she says. But the couple is taking their time planning the wedding.

“We want to be engaged for at least a year before we really jump into anything,” she says. “We want everything in place.”

Teen Mom OG premieres March 23 at 10 p.m. ET on MTV.

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