I'm not an expert at this, but yes, I believe they are now nesting. Around the 1st of July is when you should see the babies. You will then see many hummers fighting over "their" territory. I'm only speaking from my observance :)

While the females are nesting, don't they feed? I had a couple of females here earlier in the month, I know that the male was interested in them, he did his mating dance for them, but after a few days the females stopped coming to the plants and feeders. Have they left the area or are they sitting on the nest? I was really hoping to see some baby hummers.