My bmi is 17% is this normal ?

Normal or Healthy?: Normal & healthy are 2 entirely different issues. BillGates & WarrenBuffet=very abnormal financially yet many people believe they would enjoy being similarly abnormal. Normal means average/common, not good or bad. The later is more relevant. Go for excellence, not normality. BMI units are not %, but lb/ft2. BMI data=from life insurance tables of mortality by Wt, Ht & age. Thin tends to be better.

It can be: If you are eating a balanced diet of sufficient calories, a bmi of 17 is fine. Usually this bmi is normal when you have been slim your entire life.

Hard to say: If by normal you mean does it fall into the normal range expected for an adult, the answer is no. Normal is a vague term that infers a relationship to large populations. A BMI of 17 correlates with average for a 10 yo kid, but not an adult. It correlates with the bottom 1-2% of the female population. Whether that is healthy for an individual depends on a host of other factors.