This is very common. If your daughter is not underweight - don't sweat it. The less pressure you put on her to eat, the better it'll get. Also, they go in stages. My son lived on PB&J, yogurt, wheat thins and rice cakes for a while - that's all he'd eat! Then he went on a huge grilled cheese phase...then it was all fruit....then...you see - kids are weird!
Also, check the fluid situation. Make sure she's not getting more than 2 cups of milk a day. Milk fools their little tummys into feeling full when they shouldn't and can curb their appetite.
In my family, I make the rules, not my toddler - so I don't let them snack all day and not eat at meal time. I do let them have smaller snacks spread out throughout the day, but we stop and sit down for those meals as well. If they choose not to eat a snack/meal time, they must wait until the next snack/meal time arrives. This helps them know that there are times for things and that eating isn't some subconscious, mindless thing you do throughout the day. Try to provide a variety of foods, but toss in a few favs here and there.