Sister rivalry?

Shelby
My sister just got engaged a few weeks ago and is planning her wedding for this coming October. She told me she didn't want me to be pregnant at her wedding. Is it selfish if my husband and I keep trying to conceive? We have been trying awhile now and I don't want to miss a chance! But I don't want my sister upset either, I don't want to take her spot light on her special day.. That's what she is worried about. I plan on not trying next month so I am not due during Her wedding. I just don't want to start drama, but I want a baby so bad! What is the right thing here?