Very very rare to have a miscarriage at 14 weeks usually what causes a miscarriage that late is incompetent cervix something or another, basically you cervix doesnt hold the baby in right. But not a very high chance. Relax and enjoy your pregnancy. I know what it's like to worry about it. I had one earlier this year and I was worried til 12 weeks where the chances go further down. I think you good to relax now, actually worrying isn't good to do when your pregs it just stresses you out. Hope this helps :)
After 12 wks that risk drops tremendously so try not to worry and think positive, fill those thoughts of miscarriage with happy thoughts of having a healthy baby!