If you want to continue arranging your pictures in 'events', you have to use albums now. The moments view won't give you any flexibility beyond changing dates. My suggestion is: whenever you import a bunch of pictures, put them into albums immediately. In addition, I suggest creating a smart album with parameters [Album] [is not] [Any] to see all pictures that are currently not within an album, so that you don't miss any.
If you want to do it 'natively' then you have to make sure that all your new pictures are properly timestamped and, if possible, tagged with location data. Photos will arrange your pictures based on date and label them based on location data. Photos recognises events that have taken place over several days, but only if it can make sense of the location data.