Changing diaper size

So my LO is 16lbs and currently wears a size 3 in diapers. I read if it leaves red indentations around the leg, it's time to size up. She has red marks around the legs and has blowouts frequently. But according to the weight chart, she's still in the size 3. She is REALLY chubby, especially on her legs. Should i go up a size?