4 days late...taken 3 pregnancy tests and got BFN...nursing 8 month old....what cm is this?!?!

I'm so frustrated and confused. I got my first period on Jan 31st. Hubby and I BD'd on the day or day before ovulation day. But I've take 3 tests and have gotten BFN. I'm also nursing my 8 month old. I know nursing can stop a period from returning, but mine already returned...not sure if it can stop again? I have 2 old kids and once my period returned I had a normal schedule....

I've been getting this same CM for over a week now and it's getting whiter. Consistency has remained the same - lotion-y/creamy.

I'm not sure if it's normal for a period to not come back after the first while nursing...