I want to tell my vegetarian daughter it would be easier if she just ate meat
Why do you believe it would be easier for her to eat meat?
It's because she's been extremely picky for a while that it's been difficult to stretch the meals enough for her.
It's understandable that catering to someone's food preferences may be difficult, but you shouldn't expect people to just change their diets. Especially if a diet revolves around a moral belief. Try working with her to come up with meal plans that are easier for you, but she can steal eat as well.
I think she should compromise for the sake of the family.
I doubt she'll voluntarily become a meat eater. I think you'll find there are many alternatives and substitutes which are inexpensive. You shouldn't expect any change from her.