it's a conundrum.
Side effects from Tamoxifen seem to be largely reversible for many women. Ask some questions about what may happen if you start it then want to stop. It's not always the nightmare you hear about. Compared to it's big sister, letrazole, it's a pussy cat. Well, that was my experience.
Our bodies are remarkable things and the capacity to keep, or resume, doing things like produce hormones is huge. I do wish medicos would abstain from comments like the one your GP made. How can they possibly know? Menopause symptoms during chemo are very common. Low estrogen levels after chemo are not an indicator that your ovaries have given up completely and --as someone who was on Tamoxifen for 5 years I can tell you--your periods can return and all sorts of things can happen even while you are still taking the drug.
Lots of questions, an open mind and plans A through to G are the best bet. Marg