Is it possible to get implantation bleeding at 12dpo or is it spotting

[Cherry85]

I did some tests way early at 6&10dpo and they were negative.

I have had symptoms all the way through as I did with my first including headaches, cramps, nausea and sore boobs for the past 10 days. Is it possible to happen that late?

You may notice implantation bleeding anytime between 7 to 14 days after conception. So, if you have a regular cycle, there's a chance it could happen more or less when you'd expect to have your next period (if you weren't pregnant).
https://www.pampers.co.uk/pregnancy/pregnancy-symptoms/article/all-about-implantation-bleeding#

You usually don't get symptoms until after implantation has happened, so if you've been having all those symptoms due to pregnancy then implantation should have already happened. As far as I know anyway.

I had spotting and then a full on bleed on day of expected period with my second son. The midwife called it ‘breakthrough bleeding’ so could possibly be the embryo burrying into the walls. Good luck @Cherry85 I know how worrying early pregnancy can be.