I have a 2 year old and a 1 year old preemie (28.6 weeker and 34 weeker).
My 2 year old is 33 1/2 inches, and 27 pounds, and my 1 year old is 29 inches and 20 pounds. I'm only 5'1" and my husband is 5'11".
Mine was born at 35wks, but they suspect he stopped growing at around 32-33wks. He was 4lbs. 6oz. at birth (so, a bruiser in the NICU for sure, although undercooked in some places). He is now 9yo and you can't really tell him any different from any other 9yo. He's slender for sure and I think he was at around 5th percentile (once he even got ON the charts) for height/weight until he was about 4 or 5yo. Even now he's 18th for weight and 50th for height. Of course, I kind of wonder if that's because there are an awful lot of heavy kids these days and we eat cleaner than most.
My son was born at 34 weeks at 5 lbs and was not even on the charts until about 4 months. He's now just about 8 months old and is 28 inches and 21 lbs. According to charts he is right around the 50th percentile now, so his pediatrician is pretty confident he will continue at around this pace.
My daughter was 3 lbs 15 oz at just about 32 weeks. She caught up quickly. I remember getting photos done when she was 6 weeks old and she was the weight of a newborn...about 8 lbs. She caught up quickly after that. I should have pulled her off of the high calorie formula once she was almost caught up, but she stayed on until 9 months and was bigger around the middle for a long time. She seems average size to me now at age 6, and compared to her friends, but pants are always long on her, and still sometimes tight around the waist.
My 34weeker is now 8 and a slender 42lbs. My 33 weeker is 5 and a more robust 40lbs. I love that. I'm sure she'll slow down soon as she's a very active little girl and a healthy eater but for now I think it's hysterical. Weirdly enough my oldest was full term 40w1d and she's 12 1/2 now and 68.4lbs and 5foot3inches. She's not even on the growth charts for weight and hasn't been since she was about 18months or so. She looks painfully thin and gangly, almost like a colt with those long scrawny limbs. She's actually the smallest of my children pound for pound and she was my healthiest and only full-term baby. The other two had a tough start and the youngest one has had severe asthma since birth.
I have a 34 weeker, who was a big preemie at 5 lbs 15 oz at birth, who has been at leat in the 95th percentile for height and weight starting in infancy. She is now 6 years old and super tall for her age, almost 50 inches, I think.
I also have a 29 weeker, he was 3 lbs 6 oz at birth, he will be 2 next month and he just hit 22lbs. Such a difference between the two. He wears clothes now that she wore when she was 9 months old! And they were tight on her and are now loose on him. Everybody is different, preemie or not.