3 weeks to go- pressure from sister

[PK4]

My sister is getting married in a few weeks and her hen night is 3 days before my baby is due and wedding week after due date (don't even go there!!!). I'm not her maid of honour or bridesmaid. She has one of those and I've told her that it's her job to sort it out but somehow I've been roped into helping her out. It's not that I don't want to help out, but I feel why should I organise her hen night if I'm not even going to be going to it cos who knows what's going to happen within the next 3 weeks? (I'm 37 weeks preggers). I've got enough on my plate as it is! By the way, my sister changed the wedding date 2 months ago knowing when my baby was due. I'll let you make your own minds up about that 1!
Apaprt from the rant above, I know we have to sort out where we are going and what we are going to do etc, but when it comes to her wearing the 'L' plates, veil, tiara, garter etc. Is it our job to pay for that? To be honest, I can't afford to buy her these things, especially as I've got my MOT 5 days before baby due and car insurance 2 days before baby due. I'm not being selfish but that comes 1st especially as that is my means of transport to take me to the hospital.
Obviously her wedding is more important to her as it should be, but my 1st child is more important to me. We don't have a great relationship, she has always been jealous of me and doesn't treat me very well. I've been told I'm too soft and let her walk all over me. On her wedding day I'm running around doing everything for her! I have 3 other sisters BTW. A few people have told me that she changed the wedding date cos she didn't like the fact that I was getting attention and wanted the attention focused on her so she changed wedding date to week after my baby will be due.
I'm feeling just abit fed up and overwhelmed as I'm due to give birth and I feel she is being utterly selfish and a btch basically.
Or am I being the **? Do I have any right to feel like this?

sorry, I meant especially as she deliberately... etc

Cheap shops for tacky hen night stuff also some big Asda stores do cheap things - they do cheap kids tiaras in the kids party section. But get the number of the bridesmaids/friends and inform them its their job to do the hen party.

If you can find an amazing outfit that shows off your beautiful preganant figure and she will be shown up by you anyway as everyone is going to be concerned about how you are being so pregnant. If you do have your baby before again the attentions going to be on you because again people will be concerned about you being there and feeling well etc.
I think its a shame as if she'd kept her orginal date assumming it was booked before the wedding people would be more sympathic to her and try to be discret about checking on you.
It seems a shame that she doesn't have a friend who can call her up on her s**t and explain that it is much nicer to have a new baby in wedding photos as its prob the first wedding your little one would go to and could have been a great oppertunity to bond with her new niece or nephew.
My friend got married when her first nephew was 2 months old and it was great as the baby was a distraction to for the boring bits - like when the bride and groom are having private pictures etc. Then he was picked up by his other grandmother so her brother and sister in law could enjoy the evening do.

Please don't let her continue taking advantage, what does your DH think?
As I would suspect now you are having a family of your own, he will be less willing to have you being caused upset by a sister.
Especially as if you are upset by her it may take away from enjoying your time with your new family.