21 day cycles are very short. And would mean that you ovulate around cycle day 7, give or take a couple of days. Which again, is earlier than is typically seen.
And -- as John said, if you've been trying for over a year, your husband also needs to be tested.
If he's fine -- then you would need more testing to try and pin down exactly what might be wrong. (Or, sometimes, couples are just unlucky and need to try a little longer.)