Late by 7 days

Hey everyone. Im hoping for some advice. I struggled this last cycle with detecting an LH surge. I think maybe i missed it as i had a rapped surge a few times before. Not sure if its of any use to mention I had a loss in Dec last year, and felt my cycle had changed from then on, but always got my period weather 19 day cycle or 28 day cycle. But today im 7 days late on my period. We have been TTC ever since the loss so we did try this cycle. I have tested for 9 days straight every day and it is all stark negative. I have never missed a period before and this is worrying me a little. No history of PCOS, was all clear at the last US after the loss, and everything was healthy. Has anyone ever gone through something like this that might have any advice? I will be very grateful. TIA