Unfortunately they all present as female at that size. You will have to wait until she is 5-6 years old or around 4 lbs.
Unless you get “lucky” like me, my boy flashed me at 2.5 years old.
Here are some helpful pics to help determine sex when he’s grown a little bigger.
Sorry forgot to add his age. He's 3 in March. His shell is 13.5 cm, and he's just bigger than my hand.Looks small. How old? Most look female when they are too young to sex.
Around 2-3 years if you are lucky a Male will flash you. If not then it could take 5 years or more to know the sex.
If raised poorly, could take longer for them to catch up.