We have no real idea how old she is, but the vets estimate around 10. The vets also said she was a he also.
Bob was adopted by us on April 23rd 2013, he was 3 when we got him and his birthdate was registered as February 2010.
We don't have fixed dates for their birthdays, according to my facebook memories, it's been on different dates each year and is prompted my the memory.
Some years we've had McDonalds, or I've made pet biscuits, or just stuck a candle in a tin of pet food.
We did one year have a party for the Hamster.