I have been asked this in the past, but I am not aware of any broad studies that give us the data on the efficacy of hormonal methods in combination with medical marijuana that'd let me answer this for you.
(Since estrogen hasn't changed, and marijuana hasn't changed, though, this study from 1983 might be of use to you:
https://www.ncbi.nlm.nih.gov/pubmed/6296360 Secondarily, this more recent report on a study suggests that estrogen may increase how sensitive you are to THC, but not any interactions the other way round.)
Have you asked your prescribing physician for your pill? Personally, if they say it's fine, I'd trust. I keep up with the prescribing info for contraceptives, and have yet to see any additions that it IS an issue and that the pill should not be prescribed for medical marijuana users. But if they don't know, or you aren't feeling confident about it, you also can always just back up with some form of condom. In fact, given how much worry you have posted about your pill and its efficacy on the boards in the past, if you aren't already backing up with condoms, I think you could get a whole lot of peace of mind by adding them, even if you don't wind up using the CBD oil.
Sorry that's all I've got!