Hi,
I happen to have a Celltei pak o pet that I absolutely love. They have many different types of carriers including back pack ones. There are many reasons I really like the Celltei. I had been looking for 3 years for the perfect carrier, I will never need another one, it has everything.
You might check out their web site. Also the carriers are meant for the size of your fur baby.
www.celltei.com
Good luck