Cycle day 35, do I keep testing?

S

I am on cycle day 35 and have yet to start my cycle that was suppose to start on day 31. Had a blood test done on cycle day 27 and results indicated that I did ovulate. I have taken way too many pregnancy tests. One test did come back with a faint line but I have taken some since that have been an obvious negative. I am at the point that I just am waiting for my period to start. What is the problem, why haven’t I started? Do I stop testing or keep testing?