Hi Harsh,
In your domain model, you denormalized the data. Did you do this on purpose? If not for performance reasons, consider a Product entity and an Order entity.
If you keep the domain model as is, the answer is below:
The amount of products in your Cart equals the Count (Aggregate list Action) of the list over the OrderLibe_Cart association. The TotalAmount is the Sum Aggregate list Action) of the list over the OrderLibe_Cart association.
Go Make It