You can try something like this:

var contentLoader = ServiceLocator.Current.GetInstance<IContentLoader>();
var startPage = contentLoader.Get<StartPage>(ContentReference.StartPage);
var published = contentLoader.GetChildren<PageData>(startPage.ContentLink)
                                // skip container pages
                                .Filter(new FilterTemplate())
                                // skip unpublished pages
                                .Filter(new FilterPublished())
                                // ...
                                .ToList();