So, at the age of sixteen you were still being taken into the women's facilities by your mother!
No, at the age of 16 I wasn't bothered by a lady coming into the gents. You won't believe this but women don't tend to attack men or boys. Once you are old enough to go the gents by yourself with your mum outside the main concern is being attacked by another man. Not a woman.
Normally done because of a large number of women who can't be bothered waiting the facilities are inadequate for the number of women, so decide for their needs they now identity as men. And if a large proportion decide to do this, then it's too late to get extra staff in once it has happened.
I still don't see why you need extra staff. Who are they policing exactly? Either provide adequate facilities or work with the venue to get facilities updated so they are adequate.
The staff member was attacked by the self identifying women. Not as you described, the staff attacking the user.
I didn't describe that. I had made the assumption that the woman exiting the gents didn't just attack a random woman but that the female staff member said something to the woman to annoy her which resulted in said woman attacking the staff member.
If the venue has the facilities, then how do you add to them, inside the building?
You obviously can't. You look at other possibilities such as turning mens into ladies or using a temporary partition, or getting portaloos for an outside area as well etc. Women are not using the men's toilet to be difficult, they are using it because the facilities are inadequate.