I'm so sorry for your loss. I also have a twin sister. Oddly my mother gave birth to 3 Sets of twins way before fertlity drugs.
The loss of brothers and sisters is so very hard. You mourn the passing of a loved one and reckon with your own longevity. I hope you find the strength to get through this, maybe give some thanks that her passing was quick although still a great loss.
All the best.Get a ride in if you can find the time, good for inflection.