My first sentinel node procedure was negative in 2006, fast forward 10 years I had a local recurrence and 6 out of 15 nodes were corrupt. Of all the procedures I've had, the ax clearance has been the most challenging but it's probably bought me more time than anything else.
The pressure in your situation is horrible however if you don't decide today, you can decide tomorrow. Or next week when you've had a bit of time to process what you are learning and ask more questions. Leaving it until next Xmas would be unwise. Hang in there and ask more questions. Always, ask more questions. Mxx