And Janis insists the Rehab hitmaker's break from England has done her good.
"A year ago, everyone was saying: 'Will she get through this, will she even survive?' Contactmusic quoted her as telling Britain's Closer magazine.
"And look at her now. We've got the old Amy back. I always knew she'd come through it. And I know she doesn't want to go back to the drugs," she added.
Janis further said that Amy was yet to overcome her binge drinking, adding: "St Lucia was good in many ways because there were no hard drugs around, but she was bored, so she drank.
She didn't have many friends around her. But she's sorting herself out and I'm sure she'll stop drinking when she's ready.
"I've spent some time with her since she got back. She's put on a bit of weight and looks better than she has in a long time. She was busy cooking, so that's a good sign that she's actually eating. I think she's pleased to be home and I know she's happier now."