I'm sorry for your loss. You haven't missed your only chance for a baby. I've conceived three times this year and I'm 41. Unless there's a sign of a problem most people don't get ultrasounds til around 11 or 12 weeks, and had you had one it may not have shown a problem. Unfortunately miscarriage is something that just happens (and the chances of this happening over 35 are increased) and most of us never find out why it happened. Good luck for the future.