Don't be afraid to eat when you're hungry!!
Hey Lisa, I think there's a really good reason why you've had a big appetite - it's called "eating for two"! If you're eating enough and only gaining a little bit, that's fine, but it sounds like you're maybe being a little too self-conscious about how much you gain.
You know, you really are supposed to be gaining weight (some of your very own as well as baby's) so you shouldn't be afraid of that. I'm at week 22 and I've only gained 10 pounds and I didn't even start gaining that until the second trimester, but I know I've been eating enough so that's okay. Basically, your body is going to gain whatever it's supposed to (not too much, not too little) while you're pregnant as long as you're eating enough and in a healthy way.
During this time of your life, eating when you're hungry is not considered giving into temptation or letting yourself go, it's just answering your body's exhausted cry for the extra energy and nutrition it so desperately needs to take care of itself and the precious little life it's nurturing. Just remember, the standard advice while you're pregnant is that, if you're hungry, definitely eat something. All you have to do is make sure it's not junk food you're filling up on, that you get a wide variety of nutritional food and of course, don't forget your prenatal vitamins! Happy eating!