Swaddle sack or sleep sack

Hi everyone ! FTM here, so my baby is almost 6 weeks & right now I wrap her in a muslin blanket for bed & under her I have a blanket & wrap the blanket from her waist down but now that she’s a bit bigger & her moves her legs around a bit more I’m scared the blanket will push up with all her movement & end up on her face. It’s pretty cold where we live during the night, & I don’t like to leave the heater on during the night bc I’m scared she’ll get too hot, I bought a little room thermometer & the lowest I’ve seen the room get is about 64. If anyone could recommend some good swaddle sacks or sleeping sacks pls ! & also give me tips on how to dress her under it. Thank u !