You don't say why you are on Warfarin, this medication is used for a variety of conditions. The best people/person to ask is your GP, Anticoagulant Nurse and/or Consultant They know your case and history, everyone's case/condition and how they respond to medication (the theraputic window) is unique to the individual. What works for me may not be ideal or even safe for you. You could try British Heart Foundation or http://www.atrialfibrillation.org.uk/ to arm yourself with appropriate questions before seeing your GP/Nurse.
Don't mess with your meds.