New checkout step

I’m working on adding a new checkout step which is the cart summary.
To do this, first of all I create a fake progress bar adding my Cart step.

But now, when I’m during the checkout process I successfully add this step which instantly redirect the user to the next step which is “Shipping”.
My problem is: I want that ‘Cart’ step can’t by clickable or when I click when I’m on Shipping step, it redirect user to checkout/cart url

Thanks for response