Sorry you haven't yet gotten the help you need.
Need a little more info.
Do you have full, or mostly full sun on your grass?
And how do you have your mower set? Low or high?
If somebody else mows, how are they doing it?
As to what you're doing wrong, first you must stop watering every day. What you are doing is giving the shallow-rooted plants (the weeds) the perfect conditions for crowding out your grass, and bermuda is very
tough to crowd out. (I have a bunch of it, so I know!
This watering regimen/info that follows is from "Dchall" and has worked marvelously for getting our lawn established. It is a quick primer on basic lawn care.
1. Water deeply and infrequently. Deeply means at least an hour in every zone, all at once. Infrequently means monthly during the cool months and no more than weekly during the hottest part of summer. If your grass looks dry before the month/week is up, water longer next time. Deep watering grows deep, drought resistant roots. Infrequent watering allows the top layer of soil to dry completely which kills off many shallow rooted weeds and prevents new (weed) seeds from germinating.
2. Mulch mow at the lowest setting on your mower. Most grasses are the most dense when mowed tall. Bermuda
, centipede, and bent grasses are the most dense when mowed at the lowest setting on your mower. Dense grass shades out weeds and uses less water when tall. Dense grass feeds the deep roots you're developing in 1 above.
3. Fertilize regularly. I fertilize 4 times per year using organic fertilizer. Which fertilizer you use is much less important than numbers 1 and 2 above.
Everyone's sprinkler system is different. Mine puts out 1/8 inch of water per hour over a 900 square foot area. In the hottest part of summer it takes 7 hours (sometimes) to get enough water on the lawn. Usually I water for 3-4 hours. You can measure your water by putting out cans (like soup cans or tuna cans) and timing how long it takes to fill.
Watch your grass to see how long it takes to look wilty. When you see it wilting, water it right away. If it has not been a full week since you watered last, then water it longer this time. If you have runoff issues, those can be addressed.
One note from me: this sentence #1 above "Deeply means at least an hour in every zone, all at once." really gave me trouble. Maybe it's just me, but I thought I had to water my entire yard all at one time.
If you have a sprinkler system for your whole yard, this is not a problem. We do not have a sprinkler system, so I couldn't figure out how to water it all at once (without spending an entire day moving sprinklers around and watering by hand with the hose).
Then I had my epiphany!
This sentence: "Deeply means at least an hour in every zone, all at once." means that when you water, give your yard the full amount of water all on the same day, or as quickly as possible (in my case), instead
of giving the yard 1/4" today, 1/4" tomorrow, etc.
As to your question about products to treat weeds, the best thing you can do is water and mow properly. In the lawn care primer above, Dchall mentions "mulch mow"ing. If you mulch your grass cuttings back onto your yard, you are putting organic matter right back onto (and, as it breaks down, in
to) the soil.
It has been my experience (with proper watering, mulch mowing, and only 1 fertilization in almost 3 years) that bermuda establishes quickly and hangs on for dear life.
So hang in there. Organics really DO work!
**Take time to stop and smell the flowers
(or... as my ladybug refrigerator magnet says
"take time to stop and eat