What's going on in Hanyo No Yashahime's timeline?

 Okay, I have finally watched the first episode of Hanyo No Yashahime, Inuyasha's sequel, and I'm still deeply confused by the timeline. 

No spoilers, I promise.

The episode introduces one of our new protagonists, Towa, and then jumps to the past to start to explain how we got there. The story in the past starts six months after Kagome returns to the Sengoku period... But, unless the subtitles are wrong, we're told that this scenes took place ten years ago. (And given how things happen in the past scenes, I don't think there's a mistake in those subtitles)

So:

• Towa and Setsuna, Sesshomaru's daughters are supposed to be 14 years old.
• If I remember correctly, the original series took place over the course of a year. Somehow. Shikon magic or something.
• And then we had a time jump of three years, I think?

What does this mean?

1. Rin is not the mother. Thank all.
2. Sesshomaru met the human mother of the twins before the original series started.
3. How the hell is Moroha, Inuyasha and Kagome's daughter, also supposed to be 14 years old???