So, I found 2 issues with the add to cart system. When you enter a product search and click the add to cart button from the results page, and add another item from the same results, instead of adding a new item to the cart, it only adds an additional quantity to the first item selected. In contrast, if you click on the detail pages, and add it to the cart, then the new item is added to the cart. So, to get it right, you have to NOT add any item from the results page and keep clicking on details before adding it to the cart to make it work.
Secondly, when you press the continue shopping item, it goes back to the detail page rather than a new search. Something is wrong with the results page add to cart item, which I think you helped me hand code it.