I doubt your age has anything to do with it. Fertility does not decline significantly until you get to around 35. Even after that it doesn't necessarily decline - I had 3 unassisted pregnancies at the age of 41.

If you are having regular cycles you are probably Oing regularly as well, but perhaps not timing things well. If you are not already doing so start charting and then you can concentrate your efforts to the most fertile time.

Breast feeding could also be affecting things.

Above all else remember that it is perfectly normal to take up to 12 months to conceive.