As this question is posed, it's none of my business. Clear as day.
However, we both have a very rare genetic condition that affects around 1 in 10,000 people that affects fertility. My sister is very coy about the fact that she is trying to conceive and getting treatment for it. I even saw her husband at the clinic yesterday, but I was in a side corridor and he didn't see me.
As it's so rare, and what we know affects each other, am I being unreasonable to want to know a little bit more about what advice she's being given, etc?