Can you add more water to it? That would be the easiest way. Maybe you can tip the hummingbird feeder upside down to open it back up and reuse it too?
The hummingbirds would probably love your nectar but it's better to have the right concentration that is closest to what they find in flowers. I think too much sugar can cause problems, but I don't know enough other than it can make them bounce off the walls or windows.
My calculation is 4.5 x 4 = 18, that would mean you need to add 4 more cups of water to your 14 cups of mixture.
Don't beat yourself up too much. It's gonna be okay.
To keep it simple for myself, I use a 1/4 cup measuring cup for the sugar, then just count one scoop per cup of water; it works for me.