CD32, negative test, but CD28 scan showed post-ovulation lining—timing off?

My cycles are usually 32 days, but recently got irregular due to starting&stopping letrozole, and my gyno said March was kind of a “reset” cycle. My last cycle was on March 5th.

- Last week: I started having unusual navel-area cramping/movements → saw a gastro bc at some point the feeling was very scary and they referred me to a gyno too.

- CD28: ultrasound showed 15.1 mm homogeneous/decidualized lining, doctor said I already ovulated and it looked very good.. like never before & like a "potential early pregnancy"

- Today: CD32, no period, home test negative

Symptoms - & I know these are/might be PMS but just in case:

- Cramping across abdomen (including navel, which is new for me)

- Lower back pain

- Nausea, low appetite

- Breast sensitivity

- I keep getting full with light snacks but am still hungry

- One episode of light pink spotting after intercourse

What I’m confused about:

- If I already ovulated before CD28, shouldn’t my period be here by now?

- Could this still be too early for a positive test?

PS: I’ve tried to read up on irregular cycles and ovulation/luteal phase timing, but I’m still a bit confused 😅