Lol if I was that small a piece of lettuce would TERRIFY me. I'm not 100% positive, you'll have to ask others on here with more experience than me, but I wouldn't worry about giving her veggies until she is about six months old.
Is the UV down the back shining through glass or screen? If it's through glass you'll want to change that. It may not bug her now, but veileds are especially prone to mbd, and it is something that is easier to avoid than to fix.
If she is still eating lots then she probably isn't too stressed. You may find that it will take her a few months to show any other colours. My panther didn't start showing her different shades of brown and spots of green/blue until she was about nine months old.
A tip for drinking: Use water as hot as you can get it from the tap. It will cool when you mist it. Spray the whole cage for a few min, and after about 3 min she will probably start to gulp it from the air. Then, spray lightly right onto her lips (be careful of her nose, when they are babies they can get water in there very easily) and she will suck the drops off of her lips. My panther drinks this way. I've never seen her use her dripper. Sometimes she is stubborn, and it takes a few minutes of misting before she will start to drink. You don't have to soak the cage right down... just mist a few times every few seconds, and that should be enough to stimulate her.
Oh, another thing you can try is mist for a few min, then mist directly onto a leaf in front of her, if there is one.
If that still doesn't work, mist until the whole cage is soaked so all the plants and glass are dripping, then hide so she can't see you (you can drape a towel over her cage and peak in). She might go around after you are gone and lick up the drops.
That's all I can think of for now... let me know how it goes! 
Oh, one more thing, check her poop. If the white part (urate) is all white, then she is not getting dehydrated. If it is orangy then she needs to drink more.
Hope any of that can help you!