Period just arrived..

Hi everyone, 
I'm new to this. I had a miscarge at 13 weeks. Gave birth last mouth. I want to try again but argh I'm scared this will happen once again. I already have a child and therefore I don't understand how this has happened. Has anyone experienced a miscarge after a successful pregnancy then gone on to have a successful pregnancy? 
I'm scared to hear the words ' there is no heartbeat'...