10 weeks pregnant and always hungry?

So I'm 10 weeks, with my second, I'm still occassionally breast feeding my 1st. But the last week or so I keep waking up in the middle of the night hungry, and I cantsleep for a couple hrs unless I get something to eatlike toast or a bowl of cereal. I'm hardly showing I'm pregnant so the new baby can't be demanding that much extra yet!! I'm very fussy throughout the day because I feel sick and nauseous all the times, but I force myself to eat so I don't starve!! I haven't gained or lost any weight yet but it's early days but why am so hungry durin the night.I defiantly eat enough calories during the day! I know I do!!??