Javamama,
Pretty much what Phil said...
Herbs like to have, I like to say, "crappy dirt"
Just plain as plain can be... No amending with stuff, maybe a little bit of some compost because it's just okay to mix in with crappy dirt to give a bit of food and a little moisture but not much...
But they thrive on neglect really...
And certain conditions...
Alot of herbs come from areas that are hot, dry, and rocky....
So, what you should maybe try doing is stop the fertilizer...(That's why you're getting so much flowers) and maybe find a place, in the sun, that has some dirt that is just plain ole dirt.
Mix a handful of compost in (*No peat, because that's acid and most of the herbs like alkaline **Rocks are filled with alkaline or leach lime**)
And that would have been my next suggestion, was after you plant the herbs, lay a layer of flat rocks under the plant, they don't seem to like dirt splashing up on to them and their stems and leaves....
And they love sun, can't go wrong with them with sun!!
Weezie
P.S. Will you keep us posted as to how your plants are doing???