Would you be upset?

I have been with my man for almost 4 years (our anniversary is June 27th). He finally popped the question this past August and we set our wedding date for October 6th of this year.

A few months ago my sister was joking about planning her wedding even though her boyfriend hadn't proposed yet and that she wanted to have her wedding in the summer this year. I told her during that phone call that I would be pretty upset if she randomly decided to get married a few months before me. (Mind you, she has been engaged before and broke it off with another guy and has now been dating someone new for a little over a year.)

So tonight she called me and told me she got engaged! Which is great! Don't get me wrong, I'm happy for her. But then she tells me they set the date for June 29th.......

So not only did she set her date for my anniversary weekend (which we always go out of town for) she seriously decided, despite our previous conversation, to go ahead and set her date for about 3 months before my wedding. I'm honestly pretty pissed. I'm not typically a self centered person, my work and daily life revolves around helping others and this is the ONE DAY that I get to be the center of attention and I feel like she's just trying to steal my thunder. Not only that but that is going to be a big financial strain for my parents.....

Am I just being crazy?! Or is this super fucking rude of her?!?!

I don't know what to do and I need advice. :(