Do I need a splitting maul instead of a hatchet?

If your main job is splitting rounds rather than chopping or limbing, yes — a wedge-profile splitter like the Estwing Fireside Friend (a short-handled 4 lb maul) will outperform a thin-profile hatchet, which tends to stick in the wood. Reviewers consistently note that hatchets with thin geometry (Estwing Sportsman's, Fiskars X7) chop and limb well but are weak splitters above a few inches of diameter.