I watched my food intake and dieted my whole life. NOT when I got pregnant though. LOL I gained more weight than I wanted in the end but boy, that was fun. Just try to eat healthy and don't over do it, but hey, this is a special time. Have some treats!!
I feel like dieting is for after baby is born and done breastfeeding. Eat healthy food, but i wouldnt worry about "overeating" because most women who worry about overeating are those who under eat. You're pregnant honey, dont worry about eating "too much". You're eating for two. Now if you were eating nothing but junk food i would suggest watching what you eat, but as long as your big meals are healthy, then dont worry too much :)