Not to sound like a noob, but can you guys tell me how I can get more item slot things for my pets' treasure chests? It'd be much appreciated. :)

Random events, Magical Keepsake Box from the Millionaire Center, or Multi-Compartment Keepsake Box from the Cash Shop.

Oh alrighty. Thanks

Or, if your pet is not rare or has not taken a fancy/expensive elixir, you can zap with the pet zapper v2. It will slowly but surely get you there, and is much cheaper if you quest for your wizard tokens instead of buying them.