Rolling baby

My beautiful girl is 3 weeks old but she is moving around heaps when she is asleep. She kind of lifts her legs up and wiggles a bit and ends up sideways in the bassinet, or on her side, or- from this morning when her sensor alarm went off- face down in her bassinet.

I've called the nurses up who agree she shouldn't be able to do that until she is a few months old. They suggest to swaddle her and wait until she is in a deep sleep before ensuring she is back on her back, or put a sheet around her and the mattress to keep her from moving, or to put her in a sleep sack eith her arms loose so she has her arms to save herself I guess (although she'll wake herself up when she startles).

Just wondering has anyone else had this experience? I feel like I can't sleep because I'm so worried for her!