It sound like you are doing more than enough for a good job. The only thing I can think of would be on your finish coats are you reversing directions after the first coat? Roll across first, then length wise second?

"Roll across first, then length wise second?"

Yes and no. When I look to see how wet the area is, as an indication of how the paint is sticking, I sometimes go in a zig-zag or radial pattern.

Am I using enough paint? For a 500 sq.ft ceiling I used a little less than 3 gals of paint for two coats. Coverage is supposed to be 400 sq.ft per gal.

I want a smooth ceiling, but what would happen if I used a 1/2" nap roller?

but what would happen if I used a 1/2" nap roller?

I tend to use a 3/4, so 1/2 would be better than 3/8

I also use a 3/4" nap cover, but that sometimes is too big for a DIY'er to control. You may end up putting the paint on too heavy or getting skids. 3/8" nap is just too small for flats though.

Ok. I have one more ceiling to go (really more, but I'm stopping at the downstairs), so we'll see how the 1/2" nap cover works. I know I can't handle a 3/4" from garage painting experience.

I'll let y'all know in a few months.
Thanks to everyone for your comments.

e 1/2" nap cover works.

Get a good one .

Just following up on your suggestions.
Tried the 1/2" nap in the kitchen. World of difference. Looks really good.

Hired a painter to repaint the living room ceiling since my efforts were so uneven. He used 3/4" nap. Not any difference between 3/4" and 1/2" in terms of texture.

Thanks to all of you for your advice.

Since you are inside the house, is the room completely empty of furniture? Is there carpeting? I ask these questions because I would much rather go in there with a spray rig and knock it out. Although using a sprayer can be dangerous and messy without the proper experience, but they are fun to use and easy to learn. Just remember if you use one to always keep your trigger hand straight. This will help reduce the amount of overspray. Good luck.

"is the room completely empty of furniture? Is there carpeting?"

The rooms have both. So lots of plastic.
What's a spray rig? I just use a hand-held garden sprayer while I'm on a ladder. While messy, removing the popcorn is not the hard part. Getting smooth ceilings with drywall compound is the hard part.

Thanks for the suggestion.