Last night my girl had yellow/white discharge, quite a lot of it.
This morning she is bleeding, no yellow mucky discharge anymore (eg its normal looking season blood)... it is 6months to the day from her last season...
I have had multiple entire girls for over 20 years and have never seen such discharge before a season.
Her lady bits are a bit puffy too. Eats&drinks&plays normal and no temperature.
calling the vet once they open but thought I'll check here if others have ever seen similar?
I have never had a bitch with pyo or vaginitis, two things that came to mind. She is 3.5 years so not first season, I know of juveline vaginitis that can come before first season but in an adult bitch?

We had one with juv.vaginitis (which proved stubborn to cure and involved a swab/culture/ID in the end to get the right antibiotic).  But have never seen what you describe, in our adult bitches.

Why not get her spayed in another couple of months - if this should go to a Pyometra, which it could, she'll have to be done in any case.   If she were mine, I'd not risk that!!  

You made my hair stand up saying why not just spay her :-)
She is the only offspring in UK of an import girl I imported and result of about 4 years of planning/pedigree studying!
fab health&temperament...
of course if she gets pyo she will be spayed but otherwise I have plans for her.
Vet did not seem too concerned as discharge is now blood and looks like season blood, just to keep an eye on her and if anything changes, go in for ultrasound/testing...
she has had normal no issue seasons till now so fingers crossed it was pre season discharge and normal season has kicked in.

Sure if the VET had been concerned they would have given you abs.

She is the only offspring in UK of an import girl I imported and result of about 4 years of planning/pedigree studying!
fab health&temperament...

Of course that's different much as I also hope she has fab conformation and breed type (lol)    Glad it appears to be 'normal'.

All is looking ok still so relaxing a little now.
if she did not have a good confirmation, I would not consider breeding from her.
In a giant breed that is very important as they "break" very early if confirmation is rubbish&trust me, there is lot of rubbish confirmation around and even winning in the ring as nothing better is around!

>confirmation

I hate auto correct/spell check doing this, as of course it's 'CONFORMATION' as in to conform, not to confirm.