Even if her cycle is 28 days...that DOES not mean she will ovulate on cycle day 14. That is the "normal" text book answer. Even with a 28 day cycle, you can ovulate from cd 10-21. It is different for everybody. She has been trying for 2 years now, with that said there may be a good chance she isn't even ovulating.
dred613: Please see your obgyn to refer you to a fertility doctor. They will have to check you over to see what the source of the problem of not getting pregnant is.
have sex evry 2nd day or evryday if u can specially on the 14th if ur cycle is of 28 days...if its not regular than do reply ill tell u the most sensative days for getting preg..regards..
You may wish to see a fertility doctor now. Do you have PCOS? Most doctors will reconmend a paitent with PCOS with 6 months of trying regular for a baby, and those with no problems normally a year.