Hello everybody

My daughter is six months old,5 adjusted, because she was born as a month preemie. She has hovered around 5.4kg for about five weeks now, which his pediatrician says is around the normal limits. The problem is, I feel like she is not growing at all, and my mother in law is almost accusing me it’s my fault since I’m not breastfeeding. She has put on a little weight since I have started her on some solid foods like rice cereal with bananas or cooked apples, which she loved and ate almost the whole bowl. She is currently on soy formula.How much does/did your baby weigh at 5 months old? Should I be worried that my baby is still too small?