None of my magnolias have flowered, ever. They get fertiliser. They are not overly wet or overly dry.
There are several things for you to look into. Make sure that your magnolia is a variety that is hardy in your area. Make sure that it has enough sun. Make sure the soil is slightly acidic. Try adding more phosphorous in the form of bone meal. Make sure you are not pruning at the wrong time. This article has more information: https://www.gardeningknowhow.com/ornamental/trees/magnolia/magnolia-tree-care.htm
You might want to access the local Master Gardener organization. They have loads of information and assistance available for home gardeners. This link will help you locate the nearest group: