when to seek help

Bunny • ttc 4 years with 2miscarriages. Rainbow BABY GIRL born 3/10/18💕🌈 Gorgeous girl#2 born 02/19/19💕💕 baby #3 due 03/01/21
My husband & I have been trying to conceive for about 3 years. We managed to get pregnant last February but ended in miscarriage in april. We have never had any fertility tests or anything but i have no clue where to start! We are only 20 years old, i have an OBGYN but im so insecure with bringing up TTC