soya isoflavones!

I took them through my last cycle on days 2-5 80mg per day and now my af is 5 days late and I'm having negative pregnancy tests! I am worrying now that the soya has messed my cycle up I have always had a 28day cycle but a few months ago was confirmed by blood test I have borderline progesterone levels which is why I tried the soya.. Has anybody took them before and had any problems??? X