Very very sorry to hear about your loss .

Weight is important in fertility, significantly underweight women can have ovulation issues. I always understood that it was the LP length that mattered, and ovulation anywhere between CD7 and CD21 was "normal".

But I'm not a doctor and I'd go for a chat if I was concerned. Probably worth going to see a GP about the sudden weight loss, and ask for a CD21 (or in your case7DPO) blood test while you are there.