trying to conceive, ovulated day 21, 8 days late & still negative tests

HI am really hoping someone can help me I've been trying to get pregnant, I would have a 28 day cycle every month. I ovulated day 21 of my 28 day cycle and had intercourse before during and following days after. I am now 9 days late but still getting negative tests my chest is very sore and 6 days late I had some spotting. I've done a test again today and it's negative been late is something very unusual for me am i doing the test to early considering I ovulated so late please help x