Cake not rising - too many wet ingredients?

I would suggest viewing it a different way: the recipe did not fail. It is most likely performing exactly as expected by its author.

First, there is the matter of the different pan. You might intuitively think that 1 inch is not much of a difference, but you have to remember that the height of the cake will vary proportionally to the pan area, not to the pan diameter, which means a quadratic relationship. At typical cake sizes (if you went from 8 to 9, or from 9 to 10) you will have ~25% more height if you use the smaller pan. The exact area numbers from 8 to 11 inches are: 50/63/78/95 square inches.

Second, you are correct that a cake of this type, with milk and oil, and additional egg yolks, is going to rise less than other cake types. This doesn't mean that the cake is rising improperly, it means that you have chosen a cake which doesn't fit your needs (assuming you have a reason for creating a high cake). This doesn't mean that there is a simple way to get this cake recipe to rise more though; the amount of work you would have to invest is the same as in creating a new recipe from scratch. And if you succeed, the taste and texture will not be the same as the cake from which you started. So, the typical thing to do is to choose a recipe which produces higher cakes, and stick with it.