4 days late 2 negative tests..

4 days late, before then I thought I was getting my period because I had light spotting for 3 days. Nothing major just now and then when I wiped, wore pantie liners to be safe at work and never got touched. I've taken 2 tests at home and both are very clearly negative. How long do I wait till I call my doctor to see what's going on? I'm not on birth control and haven't since 2012, I have a 20 month old daughter, hypothyroidism, and had unprotected sex last month once during my fertile week. Like this is seriously annoying, I hate not knowing what is going on, either let me have my damn period or give me double freaking lines!!