Af hasn't shown.

So AF was due January 18, haven't showed yet. Haven't had sore breast at all, have only had negative pregnancy tests, last one I took was monday. Currently ttc for baby #2. I'm on cycle day 55 which I only have 40 day cycles or just a little longer. I had light spotting Sunday night and Monday morning I had Brown discharge. And very light spotting on Monday night. Only symptom is back pain EVERYDAY... Could that be the only syptom ? Do I have chance to get my positive this time ? If you've had experience likethis please coment I really don't want to keep getting my hopes up..