Hi sorry you're feeling rotten and also worried.
I can't get my head round / don't know enough about the combo you're currently on, and it may be you need specialist advice on some of the symptoms
but just to say reducing oestr definitely can cause bleeding. As has been said - any change to dose can do that. I was put previously put on a very high dose and lucky to end up with a leading meno specialist. When he first started reducing it he suggested what I honestly thought was a ridiculously small decrease - about 5%. Lo and behold I bled within 36 hours for first time in many months. Since then I've had several decreases, of different sizes, and bled immediately after some, a bit longer after others, and not after a couple. I think he said it's the decrease in hormones in natural cycle to which body responds by bleeding ... he definitely said bleeding was "normal" after a reduction.
So I hope that puts your mind at rest a bit at least on that bit ... sorry I can't help with the rest
If you have heavy bleeding or persistent including after a dose change that doesn't settle within a few months of change, it obviously needs investigating and maybe worth asking to be referred now for a scan because the wait can be long - and any GP should refer you if you tell them you have post menopausal bleeding - there's no downside to having one?