Vinceyiu,
I had 2 miscarriages before I have my son (now 3yr old). I also raised the same question, why God let this happen - also lost heartbeat at 6-7 weeks - despite my prayers. Though it was a miserable experience, now I know & appreciate "WHY".
Without the 2 miscarriages, I would probably take life for granted. I won't treasure my son as much as now. This not only applies to me but my husband as well. We see the beauty God makes in our son despite he is not a 100% easy-to-handle kid. But God changes the way we think - this is important, God does not promise to change the circumstance but how we feel to deal with the circumstance - now I enjoy my parenthood a lot more than if I have not had the miscarriages. I'd rather the miscarriages happen than God takes my son away from me now because of my negligence in taking care of him.
Don't think too much that it's something wrong with your body that causes the miscarriages. We don't really know for sure! Don't let Satan take your happiness away. What I did after the miscarriages? Physically, I consulted a chinese medical doctor for a better recovery (as I didn't know how). Emotionally, I had to heal it by myself (with God's help). I encourage u to have faith in God & pray that God will give u the best when the right time comes. Be hopeful. Worrying does not help at all. God bless,