If you are still peri-menopausal and your cycle is strong then maybe this is breaking through so you are feeling the effects of this + the HRT? Could be that your cycle is now out of sync? However that is a high dose of HRT so hopefully will get back to normal soon? See when your bleed happens over the next couple of months and if necessary you might have to make some minor adjustments to your cycle?
Sometimes if you delay taking the progesterone - and try to prevent a period by continuing oestrogen only - you would get a bleed anyway (due to your own cycle). This will likely happen if early peri. If post-meno then continuing with the oestrogen only will defo almost always do as Stellajane says.
Hurdity x