Returning to work - why am I rushing?

hi ladies I am in a similar predicament. 3 yrs ago when initially diagnosed with early BC I returned to work after surgery and worked all through my chemo and radiotherapy with minimal time off. Recently the Cancer came back, 6 weeks ago now and I am currently off work until 23 October. I had a reopening of my mastectomy scar to remove Cancer in the scar and 2 weeks later I had an oophorectomy to render me post menopausal. (I am 52). I work in a managerial position for a large company who are very supportive and encouraging me to take as much time as I need. I have income protection which kicks in after 12 weeks. My problem is my oncologist is an advocate of getting back to work as soon as possible and I am worried she will not sign me off for longer than the 10 weeks it will be in October. I am scared to discuss it with her but I know I am just not ready and I haven't even started my femara yet so how will I feel when that kicks in? Has anyone else faced this problem? I just feel I would like the rest of the year off and then ease myself back into work in January. I am still so tired and that's just from pottering around at home. I feel different this time because it is advanced and I know that now I will live with this for the rest of my life. Getting my head around that is hard enough. Sorry but I just needed to vent! I am so confused on what is the best thing to do!!