As I said, I believe trans women are trans women. I think there is space for people to be able to identify as a trans woman or a trans man. Entirely separate from being a male or a female.
I don't believe the vast majority of transwomen are a threat to women. I believe, however, that predatory men are a huge threat, and they could pretend to be trans in order to make women unsafe. (caveat being there are evil, dangerous people out regardless of sex, or gender, or identity. Some people are just bad people)
I think anyone who has gone through male puberty has a natural benefit for sport, and as such, it is important to have separate categories for the majority of sports. Whatever anyone hormones level are at that moment time, puberty itself grows bone and muscle strength that isn't lost.
I believe transwomen have their own experiences, but they are not the experiences of a woman, and they should not speak for women. A trans woman who came out as an adult, for example, has not faced the sexual harassment that comes of being a teen girl. They haven't, and never will, experience bleeding every month and the stigma that comes with it. There are many experiences that are unique to being female, and that needs protecting.
But, having a friend who is over 6ft, short haired and large chested, who wears heavy make up, and isn't traditionally attractive, who has been harassed and abused many time for "being a man", I worry about the 'vigilantes' out there who feel they have the right to police the toilets. I don't think so called collateral damage is acceptable.