It's easy to sex a Syrian
Basically boys have a more elongated extra bit at the back (that encloses their testicles). Girls have a much more rounded back end.
How long have you had your hamster? It can take them a few days to settle and a good two weeks to fully adjust to their cage - after that two weeks they become more confident. Best not to do any cleaning or changing things around in the cage that first two weeks.
She may be quite nervous if you have a cat and a dog around and she's not used to that. They have a strong sense of smell.