TTC tips and advice needed

So I've been of contraception for coming up 3 years, have not been TTC until July 2015. I was pregnant at 18 but misscarried in June 2013 ever since I've had no luck, doctors did not do an ultrasound as I was only 10 weeks, and told me to treat the bleeding as a period (using pads). Now I've tried folic acid but was making my eyesight worse. So has anybody got any tips before I go to the doctor as I'm starting to think I'll never get pregnant.