Recently diagnosed & confused about advice

Hi all, I was recently diagnosed with Endo & my gynaecologist advised me to go on oral birth control (Alesse). When I picked it up from the pharmacy, I told the pharmacist that I am a recreational weed smoker & asked about any interactions. The pharmacist told me that the pill maintains high level of estrogen in my body, whereas the weed lowers estrogen levels. Thus, the pills may not be as effective over time with continued weed usage. She said there’s still more research being done & I can do my own research as well.

So I’ve been doing my research and it says that the pill does not maintain high levels of estrogen but lowers it. There is some evidence of cannabis lowering estrogen but not sufficient. However, what I am confused about the most is how does the pill exactly interact with the hormone levels to help with endo symptoms in relation with estrogen & progesterone hormones? Unless I don’t know where to look, the internet is giving me very surface level answers (pills stop ovulation, help with endometriosis etc.) without the details of the hormonal chain reaction. For example, if the pill lowers estrogen (or increases it), how does that actually lead to slow growth of endo? Can someone direct me to any resources or help me with answer?

Thank you.