Why do I see a shadow vvfl pink line everytime I test?

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I’ve been pregnant before and had a positive test and a negative stark white test. But now that I been trying I keep getting this vvfl but end up getting my period. Sometimes is hard to see it in pictures but in person is there. I mean what are the chances of this happening every month. My period also has change. Is not as heavy as it use to for a couple months. And it don’t last too long. I’m now 39. Could it be that I’m having chemical pregnancies? Can a cyst give you those shadows vvfl? I did get checked, no ultrasound or blood work. But she check me and said everything looked fine and normal.