TTC, ovulation question

Amanda • Happily married for 13 years ❤️ Mommy to 8 beautiful kids
We started TTC last month. I've been taking the cheap ovulation test strips you can buy in bulk online. They work fine. Last month I had an LH surge on CD 15 and 16. This month, today is CD 17 and still no LH surge at all. I thought we ovulated on the same day every month? Should I be worried?
I was sick last week with an ear infection and strep and was on antibiotics, three days later I had what seemed like a 24 flu bug. I'm better now though. Maybe this affected my ovulation?