Do you bath or shower? Could be worth opting for showers to make sure everything is just washed straight away and maybe trying antibacterial body washes such as Sanex or Carex.
I've heard some doubts over products such as femfresh, that they can disturb the natural bacteria down there.
Could be worth asking for a referral to have things checked out to see if there is anything underlying or whether you are just prone and, if so, is there is anything more you can be doing.
You could concentrate on trying to boost your immune system and get rid of the bacteria causing the infections, reducing conditions which might accelerate the bacteria such as warm, damp, moists etc... by keeping the area cool and dry, maybe light cotton knickers and looser trousers and avoiding tights and such.
Do you have any other conditions like diabetes?