Make sure your mulch is deep enough. You want it to be at least 3 deep, preferably 4-6.
Also, make sure you aren’t over watering.
You might laugh but it does help I use newspapers. Lay them flat where you don’t want weeds to grow. Cover them up with dirt or mulch. It is also good for earth warms they thrive on the paper. Don’t use the glossier paper.
deep mulch and hand pulling are the best methods for flower gardens. you just have to keep at it for the entire growing season. But working in the soil is good for our mental and physical health and to me one of the joys of gardening.
For fewer weeds you need to plan an attack. In the fall or winter when your flower garden is dormant put down landscape fabric. this keep does a great job of keeping weeds down. after you plant your flowers than put down a heavy natural mulch such as the cypress you are using. if any weeds come up they are easily pulled out of the ground.