So sick of blow outs!!!!

My LO is very long and skinny. She's 14 weeks and is only 12.5 pounds. She's in size 2 diapers and it never fails she ALWAYS leaks out of her legs when she's gone poop. She isn't the type to go every day thankfully. She will sometimes go 5 days between bowl movements. She's EBF so I know that's normal but obviously when she does go it's a pretty decent amount. I've tried pampers, huggies, and Luvs and they all do the same thing. It's like they aren't tight enough around her skinny thighs to keep the poop where it belongs. Anyone experience this? What diaper brand worked for you?? I'm just sick of scrubbing stains out of her clothes all the time