For me it's someone who identifies as female, lives as female and is more vulnerable in society due to being female.
What you should say here is that you believe trans woman is more vulnerable in society (compared to men) due to being a trans female.
The trans woman experience is specific to being a trans woman.
The female experience is specific to being a woman.
Trans women aren't more vulnerable in society due to being 'female' because they are not female.
You personally call them women. That doesn't make it correct. It is a belief, not a fact. We have been told time and time again that the word 'women' (without a qualifier or subcategory) should apply to trans women as well as natal women.
Meanwhile, women are told they are 'cis women' and if we find that offensive as we are just 'women', we are called transphobic.
You fully well know that trans women are not females. You choose to say you believe they are women just as much as a natal woman, but even you must surely acknowledge that they are not female.
Are we allowed to have that word (female) or do we need to share it too?