17dpo cd 30 AF 3 days late, still testing BFN :(

Be

I know there's a lot of posts about late BFP test, but just need some reassurance.

The day before AF was due, I started with a sore throat, so now I have the cold. Extremely hot during the night, where a week ago I was still freezing at night. So don't know if it's just because I'm sick.

My breasts are feeling heavier but not so much bigger (although my hubby are saying that it feels bigger). They felt extremely sore the day AF was due, now they are just sensitive.

I had bad cramps at dpo 4 - 6 don't know if that counts for anything?

I've done PT since the day before AF but everything is BFN. :(

What is the latest you received a BFP? And is it a bad thing if your hcg levels is so low the PT doesn't pic it, although you missed your period?

When should i consider a hcg blood test?

Anybody that had similar experiences and had a full term pregnancy?