really weird situation - could I be pregnant?

[Ouchy]

We use the natural family planning method - I. E. Avoid fertile time and use condoms during fertile time.

The only time we therefore had unprotected sex this month was on day 28 of cycle, when period was due basically.

Period now 8 days late but been cramping for 5 days like I usually do when time to come on period. Done 2 pregnancy tests both negative but I'm usually fairly regular, 28 to 32 day cycle.

I'm worried! Could this be due to stress or change in exercise regime? Or could I have conceived on day 28? Help please!!

Sorry for typos

Anybody? I think I am. But maybe my symptoms are psychosomatic?

It's possible you could have ovulated very late, nearer day 28. A test two weeks after you dtd should be more conclusive

Thanks. That's what I thought