It sounds like she could have a UTI. Peeing frequently and only small amounts is a classical sign, because she probably has the constant urge and discomfort. It shouldn't be a life-and-death situation, but she will need medical attention.
Is your other kitty you had to take to the emergency vet a male? If yes, he probably had a urinary blockage and he would have died without intervention. Female cats don't get urinary blockages, so that should not be an issue.
Good luck.