Budgie experts or long-time budgie owners/breeders: Is my bird, Lemonade, a male or female?

Next month "she'll" be one year old. I bought her on August 17, 2010 but she was about 6 weeks at the time. I call Lemonade a she but I just wanna make sure. Also, she is very territorial. Every time I want to take her out of her cage, she gives me a very hard nip.