We underwent multiple rounds of ovulation induction, IUI, and IVF, all of which failed, but then we conceived naturally. However, we lost our first baby in the sixth month due to a heart anomaly. We conceived naturally again, but this time the sac formed without an embryo. We haven't done any chromosome karyotyping tests. Our doctor suggests using an egg or sperm donor, but we are not comfortable with that. How can we overcome this?