Mom's with preemies

I had my daughter 6 weeks early back in October & I know every baby is different but if you had your little one early when did they start sitting, rolling, crawling, walking?

My daughter was only 4 weeks early.
She sat up around 5 months, didn't stand until 10 months, and walked right ater her first birthday.
Her pedi says she's right on track with everything currently, but her size. She'll be 14 months on the 20th, and she's 17 lbs and 29 inches long. She's in the lower percentile for everything. She's always been "small".

My daughter was a 30 weeker. She started sitting up by herself at like 6 1/2 months, I can't remember when she crawled, but she was 15 months when she finally walked!

My daughter has rolled a few times but nothing since Valentines day. When she on her belly she has mastered scooting around in a circle. My first daughter who wasn't a preemie did everything early & I'm constantly reminding myself everybody baby does things at different times.

Once last question when did your little ones start to laugh?

she did everything 1 month later lol,
Sat up 6 months
never crawled
walked at 13 months

shes 3 now, and very bright, can count to 40 I in English and Spanish, she knows colors, geometric shapes, recognizes letters and traces...

My only problem is potty training, -__________-