Pampers Swaddlers size 8 diapers should easily fit you at 10 years old as long as you're not overweight or built bigger than most 10 year olds.
An average size 10 year old should fit easily into a pampers swaddlers size 8 diaper and even a size 7 pampers baby dry diaper.
You should also fit into a size 7 Gentle steps diaper as well.