Pregnancy Eating

I'm starting to wonder if my eating habits will ever go back to "normal". During my first trimester there were lots of things I wouldn't eat because they made me nauseous or they smelled bad. Some examples are beef, bananas, salad, chocolate,... I have now incorporated most of these back into my diet, but every once in a while I will have a day like today.
I woke up this morning and put a turkey breast in the oven. It cooked for 2 hours and smelled AMAZING. I was looking forward to eating it. Then it comes out of the oven and I started cutting it off the bone. I don't know what happened but all the sudden I was like there is no way I will be able to eat this. The same thing happened last week when I made this casserole with corn tortillas.
Its frustrating because there is NO warning. Just all the sudden I will have the entire meal done and John will have to eat the entire thing or we will freeze it because I can't eat it. I don't even know how to explain it except that if I do put a bite in my mouth I'm like a little kid trying to eat her vegetables, I can't force my self to swallow the food! Its so frustrating because then I have to find something else to eat and John gets frustrated because we are wasting food. Hes been pretty good about eating the entire casserole without complaining, or whatever it happens to be that day :).