Exactly as Teresa said. Plus, most weddings are taking place now so really your wedding sales would be earlier in the year. Buying stuff online now would be too late. I tend to get the wedding sales in Dec-Jan-Feb time frame.
Same with graduation gifts, you would see those sales earlier in the spring. Now is a lull basically in between seasons. July gets a boost if you have a Christmas in July promo or holiday items.
Late summer usually sees Halloween stuff start to gear up, September starts the Christmas season, etc. By december, people are already looking at Valentine's day or spring items, etc.
So everything usually sells a couple months BEFORE the actual holiday, event. Unfortunately for June, it's just an "in-between" month where people are more focused on being outside than online shopping.