She may just be not laying yet. Different chickens seem to start up at different points in the spring. I had an experiment once with chickens of eight different breeds. They were all hatched in June, the first one started to lay at the end of November, second pullet started a few weeks later, and so forth-- but one didn't start until February, and by the end of March I STILL had one kind not laying yet. (That was the end of my egg tracking for that batch, so I cannot tell how late in the year a pullet can go before starting to lay.)
If you look at her vent and compare it with your other chickens--if hers looks small and puckered compared to theirs, she is probably NOT laying. There are also two little bones near the vent, one on each side--you can feel their tips. If the hen is laying, they will be far enough apart for an egg to come out between them. If she's not laying, they will be close together. Again, compare with some of your other hens.
Another option is to put her in a small cage or a dog crate for a day or two. (With food and water, of course.) If she is laying, that's a pretty good way to be sure she can't hide the eggs. It also lets you check the egg color, if she lays. Not all chickens lay the "right" color of eggs, especially if they come from a commercial hatchery.
