If saying "I am a woman now because I have a vagina / I am a man now because I have a penis" will keep you safe and prevent violence on an interpersonal level then you should say it, but you cannot base your political goals off that appeal forever, your aim should be that you shouldn't have to prove your gender to people ready to violate you in the first place by being forced to give them information about your genitalia.
This can only be accomplished by destroying the structural forces which marginalized you and caused them to dehumanize you in the first place, forcing you to give them private information. This requires the abolition of legal sex, which is justified through the social fiction of "Biological Sex", just like how all systems of oppression have social fictions to justify them. You had to struggle to get in through appeals to rules made to exclude you in the first place, an appeal those who don't have easier access to surgery can't make (majority of trans people on Earth!) an appeal which can still fail through other so-called "biological" factors, also structured that way to exclude and oppress you. After your personal safety your true political aim must be that you shouldn't be put in this situation in the first place. You must become a communist.
