Does she drink from your cups? We let our daughter take sips from a regular cup at about this age.. It gave her an idea of not having to suck.. But we also let her also try straws at different times.
We did not give her sippy cup until our daughters 1st birthday.. For 2 weeks I spoke with her about how 1 year olds are big girls and do not use bottles anymore..
I took her to Target and let her pick out her own sippy cup (I purchased 2 just alike).
Then I placed it on the kitchen counter.. I let her hold it when she asked.. On the night before her birthday I told her she was "drinking her last bottle" and in the morning she would "get to drink" from the sippy cup.. When she went to sleep I threw away all bottle stuff.. In the morning I asked her if she wanted milk or juice in the cup..
At her birthday party that day everybody gave her a sippy cup, so we had a ton.. Each time she wanted a cup, I let her pick out the one she wanted to use.
We never had a problem and never looked back..