I was also the same. I had an image of me eating, eating eating. And while for the first 12 weeks i had to snack to stop from being sick (it didnt always work) after that i also had to remind myself and sometimes force myself to eat. I just didnt get that ravenous eating state. Late in preg i just craved ice cream and would have been happy (although i didnt) just eating that. LOL
Pregnancy is such an awesome time, just trust your body knows what is right.