At first I had to look it over, but the blossom is entirely like a lilac...does it smell wonderful? If so, it's a lilac! (And I'd bring in a bouquet as they'll make the room smell wonderful!)
@stownsend Take advantage of living in a colder climate! Take sturdy clippers to cut the stalks and put some in a vase; they'll last a good part of a week and they smell amazing!!!