Hey @Keyur Aghera, You get to use resources worth $300 which you can use within the span of 12 months when you get a free trial account. You always have an option to check the bill.
Also, stopping or shutting your projects is not enough, make sure you've deleted or stopped other resources that might be running on the background.
For example, you might have used a load balancer and a storage service for your project to utilize. Make sure such resources are also stopped.