On our new website the shopping cart is no longer permanently linked to your user.
The shopping cart is linked to your session.
This means that if you add things to your shopping cart in one web browser, or on one computer, they won't be in your shopping cart in another web browser or on a another computer.
It's a little different to how our old website worked, but by no means cause for alarm. Simply go to "my projects" and you'll see all the items you created there and you may add the ones you wish to purchase to your shopping cart whenever you're ready to purchase them.