The best way to get bermuda into shape is to find the Bermuda Bible online and memorize it. 3 inches is too tall for bermuda. And not wanting to fertilize any more is incorrect, too. Bermuda needs a high N fertilizer ever month while it's growing. Then after it stops growing for the year but before it becomes dormant (brown), it needs one last dose. That last one will not be picked up by the roots but will be processed by the microbes over the winter to provide an early spring green up for you.

If you have a thick lawn now, you should not need a preemergent. I have not used a preemergent in 20 years. It's not a requirement if you're watering properly, mowing low (for bermuda), and fertilizing regularly.

Thanks. I am finding out 3" is to tall but it sure is pretty ,soft, green and holds the moisture. I get a lot of compliments about how it looks. I'll cut it back later this fall.
It is thick but still lots of weeds. I'm out there everyday pullilng! And that G-- awful Johnson grass. GGGRRRRRR
I have the Bermuda bible book marked. thanks.

Mowing it under 1.5 inches will cause it to become even more dense. Dense is what you need to keep future Johnson grass out. For the current J-grass, you might need RoundUp with a "sticker" like dish soap or shampoo. That will kill the surrounding bermuda, too, so be aware and don't let the overspray get out of hand.

I got rid of some Johnson grass by mowing it. It was out on the street by my water meter - basically out of mind since the street was about 200 feet away. But I kept after it with the weed eater and it's gone now.