If you had a small baby, percentile wise, did they remain in the lower percentiles as they got older or did they eventually bump up? If so when and by how much?

DS is a peanut and before every appt I try to guess what percentile he'll be in and I'm always way wrong and he's way lower.

We just had his 9 mos and he's 11th for weight and 15th for height. I was thinking 30th for both!!! DD who is 4 is in the 60th for both....... Will ds ever be "bigger"??