Don't worry! This can be easily fixed!
- Go to the website where your shopping cart is stored.
- Copy your cart ID (see image 1)
- Visit the correct domain website
- Click the 'Transfer Cart' link (see image 1)
- Paste your cart ID and enter your email address (see image 2)
- Click 'Transfer' (see image 2) and your cart will be moved to the correct domain.