I would definitely say caffeine is the culprit. I know if I go for more than 4 hours without caffeine, I am a wreck and get a terrible headache that takes forever to go away. I never smoked so I can't say if caffeine or cigs are a stronger addiction, but I would rank caffeine right up there. It's a pretty powerful "drug"
Having said that, I'm glad you are going to get tested and find out. There is nothing better than finding out sooner rather than later. Good luck, and I hope you get good news and don't have to worry when fulfilling that craving for sweets! 
__________________
At times life is wicked and I just can't see the light
A silver lining sometimes isn't enough
To make some wrongs seem right
Whatever life brings
I've been through everything
And now I'm on my knees again
But I know I must go on
Although I hurt I must be strong
Because inside I know that many feel this way
-Creed (Don't Stop Dancing)  | 
