I would say its a magonila and there are several questions. In one picture it looks as though some pruning has been going on. If you are going to prune then early in the season after flowing (you would have had to guess by the flowering of nearby magnolias). Looks like it is still in the container. They will often have a second flowering in summer which is what you have although only one. So, if you have fed it; exactly with what? I would feed now, and a few times with something high in potassium. Suphate of Potash would be best or tomato fertiliser only.

Certain varieties, such as Sweetbay Magnolia never put out a huge flush of flowers all at once, but just a few sporadically throughout the whole growing season. If this is Sweetbay aka Magnolia Virginiana they are considered wetland plants and are difficult to keep in a pot.

Definitely a magnolia. Is it in a pot or in the ground?
Don't prune it except for any dead wood.