You need to understand WHY you are hungry all the time - and it's not because you are being rubbish or have no willpower, there are good reasons for the increase in appetite.
Being pregnant screws up your blood sugar - pregnancy hormones make your blood sugar drop faster than usual after you eat a meal, and when blood sugar drops, naturally your body tells you it's hungry.
Being pregnant also makes you crave sugary food (or High GI foods like those containing white flour), as this increases your blood sugar fast, then also causes it to drop fast (High GI foods are absorbed very quickly). This increases the amount of sugar converted into fat by your body, and keeps up the cycle of feeling starving hungry/sick and eating many times during the day. Nature "wants" you to get fat, so your baby will survive if theres a famine - unlikely in the uk .
Try changing what you are eating, if you don't know about GI (glycemic index), google it, but it's a really easy concept if you remember that the more processed a food is, the higher the GI (you should try to eat low/med GI foods and very little High GI).
So, Whole meal, whole grain, lean meats, fruit (berries are better than apples) and veg with no sugar added, pasta, not rice, and new potatoes not big floury ones would be a simple summary.
Try this for a few days, and you may find that your appetite is back under your control again - these foods will keep your blood sugar on an even keel, and may reduce morning sickness (it did for me). It will also reduce your risk of Gestational Diabetes.
Many people go off raw veg/salad in the early weeks, I know I did, but I was able to eat them lightly stir-fried veg with a little olive oil, or baked in the oven with a bit of olive oil and herbs, Italian style - as obviously it's important to try and keep up your vitamin intake.
Give it a go - it might work well for you!