@jintie thank you for bringing this up, I too am confused as to whether or not I should be having the booster. I had my 2nd pfizer late May so would be due a booster if I fall into this group.
I finished what i call active treatment (chemo & rad)s in March 2020 and have been on Femara since then and am NED, although had a bit of a scare at annual mammogram (thankfully all good).
Would be good to know if I am considered severely immunocompromised as had not considered myself in this category.
Think I may contact my GP to find out what he thinks. Hopefully this will be clarified soon. In the meantime hope you are all staying safe.