Getting pregnant

So my boyfriend and I have been having unprotected sex the past year and a half trying for a baby but have not gotten pregnant.... I might have had a miscarriage earlier this year November when I was hospitalized for severe abdominal pains but we still have had no luck since. I know we both want a baby but because of my hypothyroidism it is much harder to get pregnant... He has struggled with miscarriages in the past with another partner and I'm worried I will have the same issue. I'm in my mid twenties and never thought it would be this hard, is this normal?