have a browse round. Make notes.
Ladies can use HRT to help with hot flushes, some anti-depressant medication can ease low mood, as oestrogen levels drop off the muscles become lax so we can ache all over
and then there's the dryness - particularly around eyes, ears and vagina.
Keeping a journal about moods and diet can be helpful. Gentle exercise is important. Learning to say 'no' more so ;-).
However, your GP is 'wrong' in that you can have HRT. It really does depend on whether the cancer was oestrogen dominant, even so, quality of Life is important: after all, the proverbial bus might be along in the morning. Recent guidelines suggest that GPs should not prescribe ADs as the first line of treatment. I had breast disease and was told not to have HRT in the future and so far I've not required it apart from treatment for vaginal atrophy. But I would have pushed for HRT had I suffered as some ladies do.
Let the ADs do their work, if they help it will give you a break from the moods.