Third miscarriage in a row!

I have had two early miscarriages and a blighted ovum all within 6 months. I have no problems getting pregnant, but it never seems to work out. We want another baby so badly (we have a five year old and a 19 month old), but I am starting to lose hope. My doctor says I should keep trying as I am likely to be more fertile now, but I'm starting to feel guilty trying to get pregnant, only to lose another baby. So confused :(