The Planar Shepherd class states:
Wild Shape (Su): Your druid levels stack with your planar shepherd class levels for the purpose of determining the number of daily uses, the maximum HD and size (but not creature type), and the duration of your wild shape ability.
The Druid class spells out sizes of animals you can turn into related to druid level: Small and Medium at 5th level, Large at 8th level, Tiny at 11th and Huge at 15th.
Would a 7th-level druid, 1st-level Planar Shepherd be able to wild shape into a Large animal?