is this rude?

DS
So my sister has had difficulty staying pregnant, she's has 3 miscarriages.. she recently found out she's pregnant and has told the whole family. She's sent out group texts to everyone about her doctors appointments and stuff, but hasn't included me in the texts. At first when I heard from my parents I assumed she was making her way to telling everyone so i didn't say anything. Then I find out she invited all my siblings over to her house for dinner and hasn't said a word to me. I tried to call her to congratulate her and I left a message and she hasn't responded. That's as almost 2 weeks ago. 
 
I'm pregnant and when I found out I told her away from my family incase it was hard for her. I included her in a lot of baby stuff including ultrasounds because she kept asking and said it made her happy to be doing baby stuff. 
 
I don't feel like she owes it to me, but I am a little offended that she is blatantly avoiding telling me for no reason. So on thanksgiving we will all be at our families house and I know she's going to just assume I know, so I'm going to pretend I don't. I said that to my mom and she was like "that's not very nice." But I feel like there is nothing rude about that? She didn't tell me and can't just assume I'll figure everything out... am I wrong?