Am I being too childish?

Leslie
I don't know how many of you read a previous post of mine, so I will start at the beginning. I was married, to the best man I have ever had the pleasure of knowing and truly my best friend, in March of this year. We have been TTC since May. We have 5 kids, I have 3 and he has 2, and we all live together. Here is my question...is it childish of me to not want to try to get pregnant in the month of September because that was when his son was conceived? His son is 10, and is named after the place where he was conceived. I have heard the story multiple times of how my husband and his ex went on a trip for their anniversary, they were TTC and they actually conceived on their anniversary trip. To make things worse, his son was born the day before his ex wife's birthday. I will admit, I get jealous when I hear the story and all I can think about is MY husband making love to another woman and conceiving! Is it wrong of me to not want to repeat what they did? I also don't want a child that has a chance of being born on her birthday. She is mean to my husband, doesn't have much to do with her own kids and makes excuses why she can't see them. She refuses to even meet me, even though I am taking care of her kids. I want a baby, more than anything, with my husband but not at the same time as them. I also don't know how to tell him I want to take a month off. I really hope I get pregnant before August is over!! Opinions? And no rudeness please.