Maternity clothing

I m thinking of ordering maternity clothings but I m not sure my size. My size before getting pregnant was US6/UK10. Assuming I will gain 9-11kg (average weight gain) throughout the pregnancy, do I order 1 size bigger US 8/UK12 or 2 size bigger (US10/UK14)? I m currently in my early 2nd trimester (gainining 3kg). I can still fit into my usual clothing but waistline is really tight now and likely need new clothing soon 🥹 #advicepls