My husband and I tried (well we didn't use any protection and I really had sex alot) for almost 3 years before I got pregnant. The advice that worked for me is as follows:
1. If you smoke cigarettes, STOP!! I quit in June and by sept I was preggo.
2. Start taking prenatal vitamins. I took the cheap 5 dollar ones from walmart. It prepares your body for pregnancy.
3. I know (i promise I really know) what your going through. But i promise you that when you do get pregnant, it will be soooo special. Good Luck and God Bless
P.S. I know that sometimes age is a factor with getting pregnant, but I was 22 when I got pregnant (thats old in my family) and still had issues.