can anyone help?

We have been trying to conceive since we miscarried in April. I have had one normal cycle since and am due on today. I have had several negative pregnancy tests, and since I have been spotting the past 3 days I thought this was accurate. Today I have seemed to have 'dried up' so to speak. No spotting, no sign of period. I usually have moderate cramping but haven't had any of this as yet, just tired and a bit headachey. I took a opk today and its pretty much positive. So I am utterly confused. I know opk can pick up lh surge just before periods however I have none of the associated symptoms. Anyone else experiencing similar? X