Maybe a weighted sleep sack? My 2 week old loves them :)
We use a sleep sack versus swaddle because mine hates swaddles. I’d lie if I said I hadn’t fallen asleep before removing a blanket from her lower half like you have. We only use muslin blankets that are really breathable though, I still worry they’ll be too warm for her.
I tuck the blanket under my baby so there's no way for it to move. We also have a bedside sleeper, so I'm able to know when anything moves the blanket never moves
@J.S. I also do the same when using blankets or swaddle only the bottom half
I tuck the blanket in around my son or put him in his swaddle.
I swaddle my daughter lower half with blanket and she sleeps well at night, just wrap around lower half