If you are intending to actually free dive (that is, go below the surface and swim around while holding your breath, then return to the surface, clear your snorkel, breathe, and descend again) you will need to get a weight belt to counteract the buoyancy of the wetsuit. In salt water you add about 8% of your bodyweight to the belt - I don't know about fresh, maybe you need less. If you just want to swim around on the surface with your face in the water, that's not needed.

Do you have swim fins? Those will help a lot (in either case).