Until the end of the championship there are 3 rounds and not three months. ) In fact, Bayern still have a difficult match with Leipzig, and Dortmund with Borussia Mönchengladbach, the rest of the rivals are not so difficult. That Dortmund are in better shape may mean nothing, if Bayern win their remaining matches 1-0 they will become champions. But one point advantage is really very little and Dortmund still have chances, they need to win and just wait for Bayern to lose points.
Both teams have tough matches but Bayern still has the bigger advantage. One they are a point ahead and they have more experience to handle pressure like this. Bayern can win their three remaining league matches by any means possible just to win the league. They are used to this kind of pressure and they can handle, I don't think Dortmund can handle it.
Dortmund always fold under pressure and I feel instead of Bayern to drop points, it will be Dortmund that will drop points.
Bayern is very capable of beating Leipzig and like you said, Leipzig is pretty much Bayern's toughest opponent.
At this point, I don't think it matters too much who has more tough matches ahead of them. They will have to win all of the matches that they have left from now on. And that goes for both of them. If either of them loses even one match it is going to give a big chance for the other to get ahead in the title race.
Of course, Bayern Munich is the team with the actual advantage in this situation. Dortmund will have to work really hard to get ahead of Bayern Munich right now. Actually, if Bayern Munich does not lose Dortmund doesn't have any chance to be honest. Actually, even if Bayern Munich does draw against Leipzig, and win the other matches they are still going to be the champions.