What size Integra do I need?

Please see details below:
Size 1
From birth / 7.5 lbs to 53 lbs to approximately 2.5 years old.
Size 2
From about 18 months / 22 lbs – 3.5 years of age / 53 lbs. The exact age varies depending on the weight and height of your child.
Size 3
From about 3 years / 33 lb of age until around 6 years and beyond.

What are Short straps?
 For petite wearers.
The padded portion of the Shoulder Strap is 2 inches shorter. The overall strap length is the same.
If the regular version is sold out, you can wear the short strap version even if you are not petite.
If you are petite and the short straps are sold out, you can wear the regular version, you can do front and back carries, but not a very high back carry.