Angled house - roof help

I'm not an expert but place the square roof on the right-hand part so it goes all the way 7x7 and then pull the other part into it and adjust the height of one or both until you get something you like.

I'm not quite sure what you mean. Is it possible for you to screenshot?

I don't know if you've found a solution by now, but one thing you can do is put an octagonal roof piece in the corner, make it as big as it can go, and have the other two roof pieces attach to it. It's not a perfect solution in that there seems to be some odd clipping happening on the roof surface, but perhaps not enough to be really noticeable; and you can't extend the eaves beyond the wall because the angled roof always wants to extend a little bit more than the other roofs; but maybe this would work for you.