Aw hun, firstly
It sounds exhausting for you!
When she wakes in the night, will she settle any other way besides the boob? I found the night a good way to experiment with other ways of settling
DD. She is in a side-car arrangement, so I can respond as soon as she wakes and "shhhh" or hum and stroke her until she is back asleep. Once I discovered this, I found I could use it in the day also to help her settle. I also introduced a comforter (toy) for her to suck on. I put it in her hand as I am putting on her sleeping bag, and it seems to work really well.
Otherwise could you wear her in the sling until she is drowsy and then transfer to her bed (that way she is falling asleep in the same place as she will wake up)??
Some babies just seem to be catnappers, but it must be so, so tiring!!