The risk of miscarriage goes down dramatically by 14 weeks and even more so at 20. Right now there is only I think like a 2% chance of a miscarriage. Good luck! :)
If you've heard a heartbeat, then the chances of miscarrying GREATLY diminish. You have a 95% chance of a successful pregnancy once you hear that precious little heartbeat.
Good luck!
Truthfully, there is no "safe" point. With that being said, if you make it past the first trimester, your chances of a full term delivery is good.