Late ovulation?

My SO and I aren't exactly trying but not stopping anything either. I'm still pretty new to all this having gone off the pill in early June and having not paid attention to certain symptoms etc while my body adjusted after coming off.

According to the app, I was supposed to ovulate 9/27- 10/3 but I had just started a new job earlier in September so my schedule was all over the place...I didn't really pay attention to CM etc. Well on 10/6, I had what I definitely felt like was EWCM and we had sex.

I was sick yesterday with nausea, fatigue and a migraine yesterday. I've had pretty tough insomnia in the last week too.

Two part question:

-Is it possible ovulated late?

-If so, how many DPO can I test? I took a test this evening and it was negative.

App says AF is due tomorrow but maybe my cycle is off a week?

Thanks for any input in advance!