Mamypoko AirFit

Hi mummies! Anyone using Mamypoko Airfit (tape) and experience leaking when lo uses it? Previously was using Mamypoko Natural but we tried AirFit as i had a coupon for it. But leakage has been happening quite often when using airfit though. Could it be i need to upgrade my lo to 1 size bigger? He is 2months 11 days weighing approx 4-ish KG and is currently on NB. Should i change it to S instead?