Regarding clover, you'll be aware that glyphosate is not effective against it.  

And you will also probably be aware that the herbicides that are very effective against clover (triclopyr, metsulfuron-methyl) do have some residual effect that may well be harmful to your flower species.  

Triclopyr is one of the actives in Rainbow & Brown's GrassMate, so your current experiments are going to give you some feel for how that performs in terms of both effectiveness and impact if any on the flowers.  If you want to try metsulfuron-methyl, then look at a small pack of our MSF600.  It's cheap, very safe to use, and is effective against clover at almost absurdly low rates (less than 20g per hectare).  But again, I don't know what effect the residues (which last for about 10-12 weeks against clover and other legumes) might have on the flowers.