15 DPO- af due today

ja

Monday morning I took a test with a FR and it was a verrry faint line (like squinting faint). That same afternoon I took another test and it was much more visible but still faint. The next morning I took another test and it was back to being verrrry faint. Took another one that evening and again, faint but more visible than the morning. Today, being 15 DPO, af didnt show, so I took a test this evening it’s back to being faint but visible! What is going on?! I’m obviously showing signs of HCG so I’m pregnant.. but is this normal?? Or is this the start to a chemical pregnancy??