How do I know if she is getting her Vitamin A?

Is your 2yo breastfeeding? If so, then I wouldn't worry at all about her intake of any specific vitamins.

Does "no seafood" include all kinds of fish, so cod liver oil isnt' an option?

How about liver from poultry or red meat? Is she allergic to that as well? If you could get her to eat a small amount of liver once a week or so, that would probably give her all the vitamin A she needs. Vitamin A is fat soluble, so it can be eaten infrequently and stored in the body.

Yes liver is an excellent source. Also greens, althought they do need to be converted. I am not concerned with the conversion, as we try to round our diet out. And there is tons or A in something like sweet potato, so you have lots of Vit A to spare. I think the amount absorbed is like only 20%.