I tried adopting a pet from the pound but it wouldn't let me because "there isn't enough space in my stables" but that doesn't make sense because I do have room!

Does it have anything to do with the fact that I made groups in my stables? 

Please help!

Pregnant pets count as 2

Made a count of all your pets, and you have 16, with 4 that are pregnant. Means your pet limit should be showing 20/20?

OH!!! That makes sense I didn't notice that! Is there a way to get more space?

Thank you!! :)

Work towards building level ups to your stable asap - You can find the blueprint either in explore or in item trades for pretty cheap.... but since the materials require some hefty explore-grinding, you might as well wait until you've gotten the materials before buying the blueprint, since you might find the blueprint while looking for materials.

http://beastkeeper.com/recipes-list 
This lists all of the recipes, scroll down to Stable (Lvl 2) and you'll be able to find out what materials you need to build it.

Warehouse upgrades are also important, level it up a few times along with the Stable before going for the fancier buildings.

Work towards building level ups to your stable asap - You can find the blueprint either in explore or in item trades for pretty cheap.... but since the materials require some hefty explore-grinding, you might as well wait until you've gotten the materials before buying the blueprint, since you might find the blueprint while looking for materials.

http://beastkeeper.com/recipes-list 
This lists all of the recipes, scroll down to Stable (Lvl 2) and you'll be able to find out what materials you need to build it.

Warehouse upgrades are also important, level it up a few times along with the Stable before going for the fancier buildings.