Implantation symptoms, negative result

[FairyCatMother]

I stopped breastfeeding 10 month old DS a month ago, and about 10 days ago felt the return of the familiar signs of ovulation. We DtD, and I felt quite sure that the past 2-3 days I have been experiencing symptoms of implantation, such as cramping, light spotting and occasional nausea. I also started using the CB OPK on Thursday, and on Friday it appeared with a static smiley, which I thought could be another indicator of successful implantation due to increased LH, so I took a CB digital test just now, and it returned as not pregant, which really surprised me!

Have I tested too early? When should I test again to be sure?

I had unprotected sex 3 days before ovulation. I have been using the LH surge tests and had a peak 2 days before I felt ovulation happen (I think) on my left ovary. It was a pulling/pinching sensation. Then exactly a week from then I’ve had lower back ache which I never usually get. I also experienced really bad nausea and very low stomach cramps. Since then having hot flashes every now and then. Been testing. Today I’m 9dpo with a BFN with a test of 10miu and says you can test 6 days before your period is due. My period is due in 4 tomorrow?
Is it too early to test still even with 10miu