I hit the same wall, two trips to Boo Camp solved my problem though. Ryoma and MU (with decent skills you can get online) can do the job well enough. That said, I enjoyed the game a lot until I hit this wall.
Now I'm on Conquest. I was decided to go with hard/classic like I did with Birthright, but I was stuck the whole Sunday on chapter 10 and I read it gets MUCH more difficult towards the endgame... soooo I changed to normal/classic and I'm happy with it. I wish it could be a little harder (chapter 13 atm).