My cycle is also hard to predict. I took the pregnancy test 6 weeks after the last period. And I was feeling tender breast too.
Did u try an app my calendar? There you fill up your menses date on monthly basis it can give you a better guide. Nevertheless, you want to try testing a month later after your menses. Go qoo10 find those cheap pregnancy test kit then you wunt feel heart pain spending on clear blue for your case. But my dear, in nutrition point of view please adjust your hormones first to have a regular menses condition.