TTC under extreme conditions..?

I'm 25 years old, been married and divorced. I've had 4 miscarriages. Two with my ex husband and two now with my fiancé. (1st in 2012 I was 6wks) (2nd in 2013 I was 14wks) (3rd in 2014 12wks) and (4th in early 2015 only 5wks). 
My fiancé and I have been trying for the last two years, I have not been on birth control for 5 years. I've had my levels checked but everything comes back normal. I also suffer from a prolapsed mitral valve and murmur in my heart and require surgery. I've been waiting on them to decide on the surgery for a year now and I am becoming impatient. Should I wait or continue with my fiancé and seek out more help fertility wise? I also don't understand why I can't seem to make it through the pregnancy. It's devastating because there is nothing in this world I want more than to be a mother.
Just looking for some support and feedback from those who may have similar issues they've faced.