She may have a problem with being confined. You cannot let her out of the house though. A cat can be pregnant within one week of having kittens. Might I suggest, if there are no other cats in the house, to let her roam through your house a little... that could help ease it some. If there are other cats, is there any place where you can let her roam a little to get a change of scenery? If not, then perhaps you could open a window, and supervise to make sure she doesn't get out. It won't help her roaming-wise, but it may ease her nerves a bit if she gets uneasy.
As for the low cost spay and neuter, etc., I would suggest asking Gayef. She knows all that stuff... she's good about it.