Not eating certainly could have been a huge factor. Make sure you load up on carbs a few days before and carry something to munch on every 25-30 miles. I rode my first century this fall and followed the advise given to me by my boyfriend (an avid cyclist) - ride your own ride not someone elses. Find your rhythm and settle into it and enjoy your time on the bike. The feelings that will overcome you at the end of the ride are simply wonderful so sit back and enjoy your day.