Please please please don't worry - yet, anyway.
DS was 15 pounds at 6 weeks. (9 pounds 3 born one day early). 99th centile. As a 5 year and a bit old at school he is bang on 75th centile, and a bit above for height. Neither of us are stupendously tall.
DD - 9 pounds 3 born, a week early. No reflux like DS. Would NOT eat for days and days at birth, but then ate like a fiend. Didn't get her weighed like DS the PFB BUT she weighed 12KG (26.4 pounds - over 2 stone) at 6 months old. Off the chart slightly for height.
If she was under an HV, SS or whatever I fear they would have taken her from me. There was a show (Dispatches or similar) around that time where they showed "obese" babies, one who was munching on a whole portion of chip shop chips. She looked slim in comparison to my DD who had been on milk only.
Fast forward to now, she is 3 and a half, in age 3 clothes, and 91st centile (same as her brother) and likely to be 75th by school I reckon, same as him, and slightly above for height, once again.
We dont eat shite, we are active, we have the odd this or that "treat" though I don't call it that, its just food...no worries. They are not "obsessed" with food like some of their friends appear to be, however that too shall probably pass I would think.
Don't worry, yet!