Should I be worried about my babys weight!?

My daughter just turned 4 months on the 13th and she already weighs 18 lb! (she was born a little early at 36 weeks weighing 6 lb 12oz) that now puts her in the high 90th percentile for her weight (she wears 6-9 month clothing comfortably) I have 2 older daughters who where born full term at 8 and 9 pounds but I don't remember them being this big at this age..my baby is ebf and they where on formula so idk if that has anything to do with it I'm just worried I don't want to do anything now that will harm her health in the future (obesity) any advice would be aappreciated