If swimming feels like you versus the water, I have a tip for you. Make your body long and stretch yourself out to reduce the amount of drag your body has in the water.
Less drag means less energy expended to get to the edge of the pool. Think about stretching your body towards both ends of the pool as you swim; these opposing energies will keep your core engaged and your torso long. When swimming freestyle, slip your hands into the water and keep reaching, extending your shoulder until your torso twists and your shoulder touches your jaw. We all can't have the Michael Phelps reach, but in the pool imagining that you do can really help your swimming.