Hello and welcome to the forum. While I'm very happy to hear about your remission, I'm sorry that there are new concerns and you are in a position of waiting to see what happens. I am sure that is hard and hope that you have support around you. I think you are very wise to look at a whole approach during this time. Do they have any cancer wellness facilities near you? Many major cities have these and they offer a variety of things to patients who've had past cancer and are in remission or have active cancer currently. Things like yoga, massage, acupuncture and nutritional guidance. Your oncologist could possible refer you to a location as well as you can do your own search. A nutritionist in general would be a great idea or a holistic health care provider.
With that said, you could also discuss this directly with your doctor's office. And probably should. From my own reading, St. John's Wart has a drawback that it can increase the levels of a drug enzyme that metabolize drugs. So, while it can be effective in treating depression symptoms, there is some hesitancy giving it while someone is receiving chemo. https://academic.oup.com/jnci/article/94/16/1187/2912264 This is something to consider should you need to start chemotherapy.
Here is information on Black Cohosh. https://www.cancerresearchuk.org/about-cancer/cancer-in-general/treatment/complementary-alternative-therapies/individual-therapies/black-cohosh The article does suggest that if you have a liver issue, that it may not be the best choice.
This article has some things to try. https://pubmed.ncbi.nlm.nih.gov/11962261/ And https://chiro.org/nutrition/FULL/Can_Vitamins_Decrease_The_Risk_Of_Women%27s_Cancers.shtml
Please let me know what you think. We are here for you.