Ebf, minipill, and no period

Does anyone just randomly test for pregnancy? I am ebf, on the minipill, and still have not gotten my period. I know it's not abnormal since I'm breastfeeding and what not, but my husband and I are very active sexually (3-4x a week) and I'm afraid one method of bc is going to fail... Especially with all of these "I'm pregnant already" posts. Should I start testing 1x a month to be safe? I'm not sure when I should "worry".