I personally wouldn't worry a lot about GD crowds. I went with a group of 16 people over the first weekend of June a couple of years ago. I was the only gay person in our party, ranging in age from a few months to mid 60s. We had the Cinderella Breakfast in the castle that Saturday morning (there were two 6 year old girls in the party). We spent the rest of the day at MK, and everyone had a really good time. Be sure to book your fastpasses. I won't be going in August, I'll stick to June. And just a note: The Princess meet and greet lines were shorter than normal, as the park guests were a little bit higher percentage adults than usual. I think most gay families with kids, and more mature couples/singles will stick to June. The younger partying adults will go in August...but those are just my thoughts. And party people generally sleep later, and stay out longer at night, so if you do go in August, I'd plan to go to the parks early in the day.
But remember, crowds overall will be very busy for the next few years with all the new attractions being added. I was there in January, which has always been a slower time of year, and there were still 180 minute stand by waits for Flight of Passage. ANd long lines for everything in Toy Story Land. All the parks were busy. And I imagine the crowd will continue to ramp up as we get closer to Star Wars Galaxy's Edge preps for opening.