ttc for a year /prenatal & folic acid vitamin intake

Ana
I've been ttc for a year. Had a miscarriage at 10 weeks on 11/8/15. Doc recommended we try again 3 months and in the meantime continue prenatal and add folic acid vitamin. 
Contemplating if I should continue taking them both even after a year, we're still ttc. 
I'm afraid of too much folic acid and prenatal vitamin might be of harm. 
Anyone else in a situation like this?