I'm not a medic, but have also faced similar dilemmas, which I asked about. I had penile cancer in the past. This required a sentinal node procedure on lymph nodes in my groin.
A sentinal node procedure is specifically designed to remove the minimum number of nodes necessary. and so reduce the chances of side effects.
I wanted to know what the chances were of having one or more positive sentinal nodes. I wanted to know what the consequences would be of having positive nodes, in the event of me not having a sentinal node procedure. I also wanted to know the chances of side effects, with particular attention to lymphodema, following sentinal node removal.
A specialist nurse may not be able to give you this information. You may need to speak to a doctor. But you are entitled to answers to these questions. 
It is not always easy for medical staff. Patients often want to have concrete information. But doctors may only be able to provide statistics and probabilities.  Nevertheless, these statistics and probabilities are essential, for both yourself and your medical team, when it comes to making treatment decisions. Understanding them will help you have confidence in the choices your doctors make. They usually get it right.
In my particular case case (and all cancers and patients are different, of course) the chances of one or more positive nodes were around 20%,  the consequences of having undetected positive nodes were extremely serious, while treating positive nodes early gave a great chance of eliminating the cancer. The chances of lymphodema were very low. So I was happy to have the sentinal node procedure. It was clearly in my best interests. 
Good luck. Harry