Hey there I really enjoyed playing this! I love the aspect of customization. It's always cool to be able to make something your own in a game.
Now for feedback time!
One thing you could consider, is by instead of having to wait on the Life Stage timer to enter new phases, perhaps have it so players can choose when they're ready to move onto the next stage. As a player I really want to get into the flow of mix and matching the different components, and having a timer that controls that (especially one that feels pretty slow imo) breaks that flow.
Another thing for future development that could help amplify that feeling that you're creating your own unique pet is to have the different options result in a unique personality for your pet. It would be cool to see the pet you create grow into a personality that you can see expressed visually through facial expressions or different actions.