If any of you ladies fell pregnant within 6 months of having your baby and were breastfeeding how did you know to test?

I'm 5.5 months post partum have been fatigued for the last month or so and recently feeling nauseous and my belly feels bigger like it did around 14 weeks into my last pregnancy.

Since I'm exclusively breastfeeding I've not had a period just 3 days of extremely light spotting back in October.

So I can't say oh I'm x days late like last time.

I did test but it was negative

However multiples run in both sides of the family so I did read about the hook effect.

Did you need to get a scan or bloods to confirm?