Yen, congratulations! Great achievement, and glad you shared the details with us here.
These are good observations; took me awhile to figure this out:
Training is a lot more than just riding ---- it's also learning how to eat and drink right, both on and off the bike, maintain a good pace, know when to push, and know when to rest. I understand though how easy it is to get caught up in the excitement of "the big ride" after weeks of training, and forget to drink enough on the road. .