Anyone with previous miscarriage afraid it'll happen again?!

I know this could be a sore subject for some moms out there, but I'm a realist and sometimes a pessimist** and I'm pregnant with my 2nd child, and have a small fear of miscarrying. When I was 17 I miscarried (which I believe was God's way of telling me that I wasn't ready to have a child...which I most honestly was not).  When I was 28 I gave birth to my first son, Jackson (who is my world), and now at almost 30 I'm pregnant again. 
 
​**There's a reason for my pessimism with pregnancy (and reason why I never let myself get too terribly excited)...when I was younger, my older sister (by 11 years) was pregnant, carried her baby full term, and then when her water broke she went into the hospital and the nurses were unable to find his heartbeat...so there, the harsh and stunning reality that unexpected and horrible things happen to good people and innocent babies. 
​So here I am, pregnant, emotional, and worried about another miscarriage. I know I shouldn't think that way, nor worry about things out of my control, but I'd just like to hear from others who have been in the same or similar boats...
​Thank you!