The only area I can identify that looks in distress is the lines in the upper right corner. Did you leave a hose lying there? From your description of what you applied and the rain, the rest should recover. I would have expected problems to be related to a drop spreader, but the picture indicates a broadcast spreader was used. Either that spreader is trash, you didn't set it correctly and/or you didn't walk at a steady pace.
What was the percentage of the N in the fertilizer? How much did the bag weigh. How many square feet of your yard did you cover with it?

One of the beauties of using organic fertilizer is you can use it at any time. If you are worried about not getting enough fertilizer, then apply organics. Organic type grain fertilizers will never hurt your lawn...unless you smother the grass in it.

Why are worried about using too much? Do you think you did? Or do you think it washed over?