28 years old now....

My 1st and only pregnancy was at the age of 16, miscarriage at 3 months and haven't been pregnant since. I keep going over that time trying to figure what I did that I'm not doing now that's keeping me from the one thing I want. I had sex with my ex, we haven't been involved in 2 years, we had sex 2 days before my fertility days and I hoping it made a difference. 7 days in waiting....