Did I miss my ovulation?

Allison • 28 years old, 2 miscarriages in ‘15 & ‘16. Married 💍. 💙 KJS 6/30/18 💙 BBS 4/29/22
I usually ovulate on day 15-16. Today is CD 16, and I've been testing since CD 13. I haven't gotten a positive yet, but now the test like is getting even lighter instead of getting darker. I've tested every morning and afternoon with undiluted urine, and I thought the line would at least be getting darker but it's lighter than it was yesterday.
 Is it possible I missed my window, or maybe I haven't ovulated yet?