There is more to effective sizing than age, weight, and kgs. The baby’s build is a very important consideration. My sizing takes into consideration both current fit and future longevity so you are getting value for your money and it takes away some of the uncertainty of choice.
By all means contact me directly if there are other factors at play such as health issues (displaced hips, allergies, rashes and sensitivites, fit issues with other nappies etc).