Faint positive and then negative?

I tested a day before my AF (28th) and it was negative.

Then I had what I assume was implantation bleeding when my AF was due the next day, on the 29th feb, one day of browness when wiping! Then 4 days later (2nd March) I had a faint positive in the evening.

This morning (4th March) I had a negative.

I am getting loads of symptoms- boobs really painful, back ache, spots, cramps.

What is going on!! Am I pregnant and did the test wrong this morning? Do I just need more time?

Edit: this pic is the faint positive - I’ve had a negative since then.

With my first pregnancy I must have ovulated really late as when I went for my 12 week scan I was told to come back 10 days later! Is the same happening again?