Advice please

Some advice please. I only had one donation in my fertile window and it was the first day of my "high" (flashy face). I never Did get my "peak" after testing for 5 days. I thought I must have missed it. Anyway I am 4 days late but have tested and BFN! I have had cramps just like I'm due to start AF but nothing yet. Has anyone had negative tests and eventually got a positive after a long time? I'm trying not to get my hopes up. This would have been the first cycle since having a HSG... Does that affect your cycle?