dnd 3.5e – Did the Planar Shepherd and Druid levels stack up when you set the size of the creature to which you can cast Wild Form?

The Planar Shepherd class states:

Wild form (Su): Your Druid levels stack with your Planetary Shepherd class levels to determine the number of daily uses, the maximum HD and size (but not the creature type), and the duration of your Wildform ability.

The Druid class describes the size of the animals that you can transform in relation to the Druid level: Small and Medium in the 5th level, Big in the 8th level, Tiny in the 11th rank and Huge in the 15th rank.

Could a Level 7 Druid, Level 1 Planar Shepherd, turn into a big animal?