Please don't be so mean to yourself! My first fast was a piece of cake and I did 13 days like it was nothing. Then the next time I did only 2 days, then stopped. then I did four and stopped. then one day a couple of times. On these times I realized it was an inappropriate time in my life to be fasting. I listened to the wisdom of my heart, not my ego.
Now I am on day four again, and maybe I will go to 10 or maybe I won't, but either way I am happy about what I've done so far.
5 days is amazing and I agree with hopinso that you will be better prepared next time to prevent the same occurance.