The past 3months i have ttc. i've used the plan b pill for about 3-4 times in the same yr can this be a reason why i haven't gotten pregnant.

Relax.: From your question, i presume you did not desire pregnancy previously but now you do? If that's the case, do not take any more Plan B or birth control and try with regular unprotected vaginal intercourse (2-3 times/week, preferably around your ovulation) for at least 12 months before getting concerned about infertility. At your age, expect 25-30% chance of conception each cycle. Folic acid 1 mg!