I use Listary (friend's app) for the same thing but it's a paid app. GroceryIQ is a good free app for that.

I think your app adds complexity where it isn't needed. Tag tags? Hard to get. The whole terminology is not clear. If you want to group items, call it Group.

A good feature would be to recognize items as you type them and add to specific aisles (produce, bakery, etc). That way you won't need groups.

I also think the icons are not very clear and the delete function should be a simple swipe sideways.