Overnight diapers homemade

I've been trying to find overnight diapers for my daughter because she is 6 months old and sleeps basically through the night and when she wakes up she has peed through her diaper in the morning or poops through it and has a blowout which she has never done before in her life they only make overnight diapers in size 3 and she barely fits in size 1 so there's no way she's going to fit into a size 3. I'm trying to figure out the best way to like not have this problem until she can fit into diapers that make overnight diapers but until then what have other parents done or ideas have you heard of I've heard of putting like a sanitary pad for periods in their diaper but that just kind of makes me uncomfortable because I don't know what kind of chemicals and what matter in those and they're not made for a baby's bum and then I thought about maybe putting a size two diaper over her size one diaper but I don't know if that would be too uncomfortable or if that would even work