If you are seeing male genitalia it is a male. Plastron concavity is variable and sometimes it doesn't become obvious until later on. My Bert didn't show any concavity until he was around 9. By ten or eleven you should be seeing some concavity, but stranger things have happened. There will only be concavity toward the rear of the plastron, not the whole thing. Can you post a pic? Take it from an angle, rather than straight on, so we can see it better.
i will post a pic soon unfortunately my rents have gone on holiday and taken the camera with them i only have a pic of him is family pictures of his face and his shell he does have some pyramiding unfortunatly but i have only just found this forum and we have started spraying him to stop further damage
hes just had some pallets so excuse his dirty face