Hi
sistersadness, welcome to the forums!
Unfortunately, you might not be able to recover your pictures if you've already taken more pictures with the camera. However, all might not be lost! Try this software
HERE. Just use the free trial. You can also try other software programs by doing a search on Google and typing in "photo recovery software" (without the quotes). If one doesn't work, another might, but it's unlikely. If after the second attempt of recovering your lost images fails, then I'd say that you're out of luck
The problem with the small keychain cameras is that they're more of a novelty item instead of a "hi-tech" device. So, you're not getting the quality of a full blown digital camera, which is what you might be experiencing, where it might be deleting other images to make room for more, as where with a camera it will tell you "Unable to take picture, card full".
Digital camera's are fairly cheap nowadays, specially for a basic small point and shoot one. It might not hurt to buy one and stick it in your purse (or backpack or what have you).
Another route is to pick up a camera phone. This will allow you to snap photos whenever you want, and email (picture text) them to an email account for printing or further emailing. It will also eliminate the need to carry around a seperate camera that you'd worry about losing or breaking!
Hope this helps!