Am I overreacting?

I was talking to my mother in law today and she informed my husbands brother and our sister in law were planning a vacation the third week of September and invited my mother in law and father in law to go with them.  Our baby is due the second week of September so their argument is our nugget will already be here when they leave. Number one, there is no way to predict when our baby is going to come. He could be late. Number two, why is my brother in law and sister in law planning a vacation at this time in the first place? We've made a point to be there for the birth of their two kids. Is it crazy for me to be upset? I'm definitely already emotional bc I'm preggo but also bc it's very possible my mom might have cancer and I am so distraught over the thought of losing her. How would you feel?