Is it wrong for me to not want my sister to marry i'n the same year as me?

I've been planning my wedding for 12 months and we get married i'n 18. We've been together 9 years. My family haven't got much money so were paying for the wedding ourselves. I don't think my family can afford 2 of everything with having 2weddings i'n the same year? They still have to pay out for travel,accomodation and outfits for themselves! My sister has been engaged 6days and announced she's to marry same year as us(they've been together 6months) it also makes everything harder for the brides as we will be sharing the limelight, it may sound selfish but this is a big deal to mr and my family, she's now got my mum lying for her and I don't know who to trust, am I being out of order or does any1 else think I'm right to want to be special for once and consider everyone elses expense?