Not sure if the new cat is using her box?

I have a new foster, and I put Fresh News litter in her box, since that's what the shelter uses. I picked her up on Monday, at 11am, and she messed her carrier on the way home.....But I haven't seen solid waste in her box since, and the only sign that she's been in it is indents. I don't see any messes in the room, and she does move from closet shelf to under the bed....so I don't think that she's going elsewhere.....maybe it's just that this litter works differently than clay? I'm also less concerned than I could be because i understand that she's barely eaten anything for 2 days, due to the stress of leaving her little cage for a room with hidey-holes.

Has she done anything yet? It's not unusual for a cat to not use the litter box for a day or two in a new environment, but you don't want to let it go too long. You might try putting out a second litter box with a different litter. Mine seem to prefer a clumping litter with a sand texture.

Not eating for a couple of days is not terribly abnormal after a move like this, but if she hasn't eaten anything since Monday I think it's time for an intervention.  Can you get her to eat out of your hand, or eat treats?  Has she thrown up?  And is she peeing?  The lack of poop is probably because there's nothing to poop out...plus it's possible one of those hidey holes is concealing some little treasures.  

I suggest trying to get her to eat something, anything:  treats, boiled chicken, freeze dried food, tuna or sardines, meat baby food (no onions or salt), whatever you can find to get her appetite going.   If this fails you may need to get her to a vet.  You could also try syringe feeding smooth canned food or baby food blended with water.  If she's been off food long enough she might not be able to start eating on her own.

I expect that once she settles in and starts eating, it's likely that the litter box issue will solve itself.  Otherwise, adding more boxes to see what her preferred litter & place are may help.

I found wet pellets today. called the shelter and told them that I'm concerned-they suggested wet food to get her moving. 

She's eating any treats that I give her, had some tuna the first day, and about 1/3 can(5oz cans) of Friskies each day since. She's not touching the Science Diet that the shelter sent her home with, but I don't blame her- the stuff smells really un-appealing, and is made mostly of by-products and corn. I'm going to put her on Wellness with my cats instead, since she ate the little bit that I gave her just now. I figure that her hunger-strike has already wreaked havok on her digestive system by now, so I can probably put her on a wet/wellness combo diet without hurting her more.....I'll just mix a little SD in to ease the process.

Sounds like a plan.  If she doesn't take to the Wellness I'd suggest boiled chicken or Fancy Feast - don't know what's in FF but cats love the stuff.

Also where are you feeding her?  It might be near something noisy, e.g. near the washing machine or fridge, or too much out in the open.  Try moving the bowl around.  Also try feeding her on a plate, if her whiskers are touching the bowl she might not like it.

Good luck!  It sounds like it's not an urgent situation as she's peeing at eating enough to get by, so you have time to sort this out.

Right now I'm feeding her right there in her closet-nest. she likes to sleep on the one shelf, and the litter's on the bottom. I put the food on her sleeping shelf with her. She does have to venture out for water though...I don't want water spilled on clean clothes so it's on the floor just outside the closet.

We had a breakthrough tonight.....she left the closet, and ventured out of the room. While she was out she found the boys' litter boxes and used one. I hope that doesn't cause it's own issues, but I wasn't about to stop her from using a litterbox. I'll clean it tonight. The boys aren't hostile or anything, so I don't think it'll be a problem.......

That's great!!

The food may be too close to the litter box.  Try moving it farther away, like where the water is but not next to that either.

I understand your logic, Sophie...but putting her food near her water would put it closer to her litter box. Right now it's a few shelves up. I did move her food now that she's venturing out, and put it on the desk where I can watch to see if it's being eaten. General rule is that she's consuming everything but the science diet that they sent her with. If I put down a bowl with wet and S/D, she eats the wet portion. Same if I put down Wellness and S/D.....I think that she just doesn't like the Science Diet.