Sounds like a proper bleed and most likely due to the higher dose. Even though it is probably due to this (continuous combined HRT can cause unpredictable bleeding at first and you are now on a higher dose). I would ask to speak to the doctor and if necessary ask for an emergency appointment just to check what you should do. You should not have to wait until Dec 10th nor wait for a cancellation. It may also be that you have fibroids or a polyp which is another explanation for bleeding on a higher dose.
It may be that you would be better off on a cyclical HRT which gives a predictable bleed.
Have you been told to use the estriol cream nightly for 2 weeks and then twice a week thereafter? That is the standard regime when you start the cream.
My husband pokes his head round the door where I am sitting at my computer and looks at the screen and says - Menopause Forum again is it? I tell him I've only just logged on which is usually true - he just happens to walk in then

. Not that it's anything to do with him what sites I visit!!! I would love the web designer to change the colours from green and yellow to something less obvious so it looks like any other website/forum!!!
Hurdity x