So confused!!

So I’m on the combined pill and have been for a while! I’ve been getting regular periods since I started it, last month I had no period what so ever and I’m due my next period!

I’ve been taking tests and all have been negative but a 2 days ago, about 4 days after having sex with my then boyfriend I had this weird spotting, was barely anything just a little blood when I wiped then nothing!

I took another test today and nothing, has anyone experienced this? Am I testing too early or is there something wrong?