Sorry are you taking an estradiol patch AND a combined pill, Yasmin?
These should not be used together.
Ethinylestradiol is much more potent and I think there's 30mcg in Yasmin.
The progestin component may not be enough if you are on a HRT patch as well.
This may well be the cause of your bleeding, and it is unlikely to be anything sinister if you've had a recent pelvic scan and your smear is in date, however please speak to your GP or specialist as it is not safe practice to be on an ethinylestradiol based combined pill in addition to menopause hormone therapy.