I Am Taking Warafin 2.5 Daily . My Inr Was

I am taking Warafin 2.5 daily . my inr was 1.3 yesterday . the nurse upped my dosage to 3.5, I am very careful about not eating dark green veggies. I have friends and family member that see their DR. every 3 months . I go once a week for the INR. started Warafin in March Why do I need to have my INR checked weekly. WT 145lbs 77years,