Hi Kombigirl,
I was in a similar situation as you since the last 7 weeks. My family & I too had booked our overseas holiday but the surgeon advised us to cancel our trip & he even gave me a letter so I could get my refunds of my air tickets. Things move pretty fast. It is 3 weeks since I had my mastectomy and will be starting my treatment next month. The surgeon advised me that I could travel in 6 months time. So hopefully will do next year but for now I am focussed on getting better.
Just one word of advise - please stay positive & you will come through this phase easily.