NTA. You didn't announce your pregnancy when she announced her engagement and you didn't announce the pregnancy at her wedding - both of which would have made you TA. Your sister is being somewhat unreasonable, she's basically saying "how dare you get pregnant during the year before my wedding - there can't be two happy events this year. " She had way too many examples of when the baby/pregnancy could get in the way of her wedding stuff to be considered even remotely reasonable.

People don't get a notice of a pregnancy and 'save the date' - and just toss the 'save the date.' They don't think "a baby is coming, can't possibly remember that a wedding is also coming too. " You don't RSVP to a birth so even if everyone got both the same day.... I really doubt she needs to worry about this. And obviously you all can coordinate he showers so they don't overlap. That won't be difficult nor should it be a reason to be concerned. It's like she thinks people can only manage to think about one thing at any given time.

As for the baby at the wedding. I can kind of understand this part, especially a newborn that may only be 2-4 weeks old at that time. Weddings are loud and these two things don't always mix. Although my SIL brought her baby to one of my brothers weddings (he was a couple months old at the time) and he was fine. I could also understand your sister being concerned about you two making it since the due date is so close. And being disappointed that your wife may not be able to join in on the fun of a bachelorette party..... But to be angry? And upset over it?

What exactly does she think you can do about it now? So she can either get over it and be happy for you or potentially ruin your relationship by being selfish.