Actually, it is very common and it's not your fault. It's happened to me twice too. But, now I have two adorable kids. So, please don't give much pressure to yourself.
Probably, it's an arrangement by God to urge you to prepare yourself a stronger body before receiving a baby. You know, bearing a baby is not as difficult as bringing it up. The road ahead is very long. So, take the time and have more rest, eat healthy food, do something that will please yourself...