It it selfish..?

So, my sister and I are both pregnant. I'm due in September and she's due in December. 
People were really upset with me when I announced my pregnancy because my son will only be 20 months when my baby is born. No one really cared or asked about me or the baby until we found out it was a girl (we haven't had a new girl in the family in 6 years. But we have 8 boys all under the age of 5!) 
So, after we announced the gender people were excited... Then my sister announced her pregnancy. She recently got married and she told everyone she wasn't able to have kids (which wasn't true. She just diagnosed herself because they had been having unprotected sex and she never got pregnant). 
Ever since she announced her pregnancy that's all anyone talks about. 
It doesn't bother me that everyone is so excited for her.. I had my moment in the baby spotlight with my first.. But she found out what she's having today and is announcing it Saturday. And part of me secretly hopes that it's a boy. 
I feel terrible about it, but I feel like the only reason people even cared about my baby is because she's a girl and if my sister has a girl they'll overlook my baby like they did before.