It may be that they decided that Tamoxifen was the one for you as it is cheap as chips. I hope that is not cynical. I had two and a half years on Tamoxifen with all the attendant side effects, including weight gain. Which was denied by the Drs but common amongst women taking it ,and then I was switched to Anastrozol which I took for about three years. I was better as far as the flushing went but did have aching joints.
Let's be frank, no long term drug use is without any side effects, but 15 years later I am here to tell my story.
Good luck with it all.