“Requiring a mother to be female is a narrow definition?”
No, requiring a mother to have given birth is a narrow definition.
“Women who are parents are mothers. Freddy is female and a parent so is a mother.”
You say that as if it’s really obvious and accepted by everyone but non-birth mothers in lesbian couples spend a lot of time asserting and negotiating their right and wish to be to be a mother (not everyone does, obviously), against systems that are set up not to recognise them, internalised beliefs about what a mother should be and in some cases outright hostility and discrimination.
“The word says nothing of personality, has no value judgement to make on feelings, on masculinity, on femininity. It's ONLY the word for our bodies and the act of creation we've both done with them.”
That is clearly not true. ‘Mother’ is a term used for women who have given birth to a baby, but it is also a word that has many other uses, and different layers of meaning and is deeply connected to ideas about both femininity and what it means to be a woman In society. As much as you keep saying it’s a neutral scientific term simply related to the existence of ovaries and a uterus, it isn’t, and will never be.
“So, if mother, according to you, is an expansive and wide ranging term for acts of nurture”
It’s not just ‘according to me’ – it is used in that way, but it is also connected to womanhood. Freddy is a trans man, so he would prefer to use father. Other people would prefer to refer to a ‘parent who has given birth’ on official documents, whilst being free to choose whatever term they like in daily life. Clearly you don’t believe that he should be allowed to do that, which is up to you, but pretending that ‘mother’ doesn’t have meanings other than ‘has given birth to a baby using her uterus’ is very odd to me.