Not in your DDC, but every baby is different! My son was born at 29w4d, and he never gained fat rolls at all. He finaly got a milk belly, but only got like barely one thigh roll on each leg, if you can even call it a roll.
It took him until 12 months old before he even got onto the growth chart for his actual age (most babies on it by 6 months, from what I was told), and he was always 20-25% for weight adjusted age during that time. I had a friend who also had a 29 weeker, and that baby chunked out big time!!!
Now, my DS will be 2 years old next week, and he's actually 30 lbs, which is a pretty good weight for actual age. He's been at 50% weight actual age since 15 months. At that point, he just jumped way onto the chart and really packed it on! But he's still not chubby like alot of kids. He seems to be all bone and muscle (he's a BRICK when you pick him up).
Looking at my own weight at various ages prior to 1 year, I found that he was following my EXACT weight patterns in the first year! Amazing! What I was at 9 months (when they said I was "underweight", btw), he was at 9 months adjusted age. Pretty neat. So obviously, his low weight in the first year was due to my genes. And now he has gained his father's weight genes, being a baby brick in the toddler years.
So don't worry about other people's babies being bigger than your own. The bf'ing may or may not have contributed to the difference... I've seen chunky formula babies, but I've also seen some pretty chunky bf babies! I really think it's more genetics than anything else. And being low on the weight chart doesn't mean much. Someone has to be down there, right?
As long as your kids are obviously developing and growing and hitting major milestones, I wouldn't worry AT ALL.
And active babies tend to burn up the baby chub sooner too. Another friend of mine had a son who started walking at *6.5 months*. I kid you not. And yes, he was very low on the growth chart for weight because he was SO active at such a young age. But he was very obviously thriving if he was meeting such a big milestone that early!!!