Late period, negative test, achy breasts . . . ? Wtf.

My period is 7 days late as of today. I tested at 5 days late, fmu, and it was negative. I feel fine other than the girls started hurting yesterday, other than that, no PMS or pregnancy symptoms. Periods are regular, give or take a day. Question is, has anyone else tested 5 days late with a negative, and soon after gotten a positive? I do have endometriosis, but with that I always have horrific pain right before my period, and this month I haven't had much of any. Just confused and curious what others think. . . Thank you in advance