Missed Period...still getting negatives.

Ugh, I just want my body to be normal. Husband and I have been Ttc for about 6 months now. Well, I should have gotten my period about 16 days ago. Nada! I’ve had a minimal amount of nausea and I’m always tired. 4 test in 16 days and I’m still getting negatives. It’s not uncommon for my cycle to come late or not at all. In 2011 I went from January to August without a period and was not wc. I do have a healthy 6 year old, but I was 14 days late when I got a positive with her. Just whining!