Art is cute and I can see some potential in the premise, though the whole concept seems a bit convoluted.
I also believe that there are some mechanics that don't really "do" anything to make the game feel better. For example: why do i have to "wait" for certain firework types to be delivered? Couldn't those just be there, at all times? Is it so that the player cannot just throw a bunch of them to the inventory?
Don't feel discouraged though! Now you see the benefits of playtesting :)