Back at work

Hi, I finished treatment for a grade 3 Breast cancer end of July. Had lumpectomy, chemo and radiotherapy. Went back to work in October, I still feel tired a lot of the time, exhausted by the end of my shift, I’ve actually felt as if I could fall asleep while driving home often. Am I being pathetic, should I be coping better by now? I feel only others who have been there can answer that, I’m not looking for sympathy, but appreciate any opinions x