Sounds like "Overtime" by sam (rated MA)
www.dokuga.com/fanfiction/story/9792/1?author=13198
Before the defeat of Naraku she made a deal. She wanted to help demons survive the 500 years between the past and her present but after a long trip through the well and discovering something new about herself Kagome might be in over her head at her office job.

Sadly, it is incomplete and has not been updated since August 2015

I'm drawing a blank on the name and I'm sure it's in my faves ... But the story goes like this Kagome makes a wish and is sent to the future
We're demons exist but in secret. Sesshoumaru and unusual find her she takes her death In order to work with the demons hiding. Her brother comes into his powers as a mink and kills a demon. Her and Sesshoumaru mate
That's all I can recall of the story
Please help


Also can't recall the one were she sent future back into the past and becomes friends with Sesshoumaru in the past and only gives her her last name and she's permanently sent to the future were she meet him again

The second story could be Unspoiled by forthright
dokuga.com/fanfiction/story/2508/1 (Rated T)

Yep that's the one thank you