Need some advice...

Ok, so here's a little history. In January we found out our little girl had Turners Syndrome. Her heart stopped at 21 weeks and I had to be induced to deliver her. I have had a period every month since but they have been less than predictable. The last two months have been within a day or two but this month I'm 9 days later than my "expected period". I have taken multiple tests only to get negatives. (We are TTC) Is this normal or something I should go to the doctor about? 😳 Thanks!