@eyemamom - @oregon101 has a good suggestion about being flexible. Weather during our trip was quick nice and we had a lot of sunshine during our late May trip. There were a couple of days that we had mist but it didn’t prevent us from doing anything. Another warning - Iceland is expensive when it comes to food. Here’s our trip report with details of our trip if you’re interested in our intinery. https://www.tripadvisor.com/ShowTopic-g189952-i223-k9632651-Our_May_June_2016_Trip_report_long-Iceland.html
Hope you get to go! I would go back again!