Sign language won't help your daughter to actually say the words and can actually delay her language skills more. Your daughter is old enough to talk and if she can say words and uses other words well I wouldn't worry. My daughter was a good and early talker saying 15-20 words just after her first birthday. But once she learned that non-verbal communication was easier for her and more effective on us she stopped trying to talk almost completely. It wasn't until she was about 2 years old that she finally started talking again. She'll be three this October and she's still having trouble with pronunciation, although she's doing much better overall with her talking. Having had one of "those" kids, I'd say just wait it out. Do what you can to get her to use as many other words as possible and make sure you're always saying the words she should be using. She'll get over it eventually, phases like this aren't abnormal. But I would suggest that you don't further her reliance on non-verbal communication. Sign language can be a great tool for younger babies and toddlers who honestly can't say the words, but once they start talking it's important to focus on developing those verbal language skills rather than the non-verbal ones. I know of too many kids who relied solely on sign language and even though their parents said the words with the signs they were delayed verbally because they never had to put out the effort to speak.