Decisions & Pregnancy are a bad mix

I am at a loss. Now I know why I am on my third pregnancy and have never had a baby shower. Pregnant women don't do decisions well.
Ok, so since this is more then likely my last pregnancy my family and I really want to have a baby shower. I've always wanted one, and never had one. First pregnancy was a teen pregnancy...and...yeah. Second pregnancy had one scheduled but I canceled the plans for it when Morgan passed away, I just couldn't do it. We did have a welcome home party for her though. It was nothing like a baby shower though. My sister made dinner, my family came, one friend and my mother in law we ate and they all got to see Maddie when she came out of the hospital.
Howard wanted to throw one for me this time around. I know that is not proper ettiquite but he's my husband, and most men don't want to be a part of this type of thing, anyone who knows him KNOWS he is not most men. He figures he knows what I like and what I don't like. He would be able to be a part of the baby shower (because he does actually want to be) but still be able to make sure it ran smoothly.

But now a wrench has been thrown into it and I am not sure how to proceed. While having lunch with my sister the other day my sis mentioned throwing a shower for our pregnant cousin. My mother immediately asked about a shower for me. Now, I love my sister but we are not close by any means. At all. I frankly didn't want to ask her for anything, and now my mother has her thinking she needs to throw a shower for me and of course being the politically correct person she is, she agreed immediately.

So, she wants to throw a shower for me on September 20th (no she did not ask me about the date, but that is the only time she has time to do it). This will not work for many reasons. My 4 besties from high school are not able to make that date because they are going out of town. Not only that but they ARE out of town so on a Sunday they would have to drive here then straight back then deal with work and school on Monday morning. Not too fair. My oldest bestie is moving into her brand new house either the weekend before that OR THAT WEEKEND so she wouldn't be able to make it either!

So what do I do?
Do I tell my sister 'Thanks but no thanks' and have her offended and my family won't show up at my shower if I throw one?
Do I just allow her to throw it and just deal with the fact that my friends won't be able to make it?
Do I have the shower thrown by her then throw another one that will work for my friends schedule? 2 showers?

ANYONE who has an option on this, pleaseeeeeeeeee give me a piece of it. I need help, maybe professional help.