When I do this I just get a cart that is in the webpage itself - it does not get added to the email body
If you are using one of the local Payment gateways like PayPal Payments pro, you can add the Universal Email behavior to the confirm page.
On the To tab, click the lightning bolt next to the email address, expand the session collection and select the WA_eCart_CheckoutForm_Email session variable.
When creating the email body, go to Insert -> eCart -> Cart Display Manager. for the cart display type, select email friendly.