After a year of trying, you may want to see a doctor just to have things checked out. They can run some basic tests. Sometimes there can be a problem that can be fixed fairly easily. Are your cycles regular?
If you don't want to go to the doctor you could try a fertiltiy monitor. I think clearblue makes the only one...My girlfriend just got pregnant from using it...You can find it at drugstore.Com and amazon i'm pretty sure