If you hadn't named her already (eventually found out you had, scrolling through the thread), I was going to suggest "Alf" !! According to Radio 4 today, it is one of the most favorite dog names !!!!! And one could argue it is sort of trans-gender. Anyway, too late!
Rhosyn is much better.
In passing, went to see my ex's 4 week-old pups today: her doggy-mum and the 4 pups doing extremely well. Apparently, doggy-mum often dumps largest pup away from the others for a while, so it cannot compete with siblings when suckling, OR she takes smallest pup off to a corner and suckles it on its own away from the other three. What a brilliant mum!
However, there is a degree of confusion about whether they are 4 males or 4 females: they sort of look like males with very tufted/hairy "protrusion" on lower part of tummy, BUT we can't discern remnants of umbilical cord. Surely umbilical "scar" would still be very noticeable at 3-4 weeks? If so, then they are probably 4 females!