Teen Mom Thinks Prison Will Save Her Life

Sources tell us, immediately following the reality TV star's incarceration, her last drug test came back positive for the opiate-based drug Suboxone ... a highly addictive drug similar to Morphine.

Law enforcement sources tell us, Portwood admitted she can't control herself around the drug -- even buying it off the street during her court-ordered drug program.

We're told Amber believes prison is the only way to get clean because it will force her to kick the addiction cold turkey.