Pregmate line stealer?

Does anyone know if the pregmate brand test turn into line stealers eventually? I’ve been faithfully taking a test every day for a week or so and although I know I am very much pregnant this is my fourth pregnancy this year. They’re just as dark as the control line right now and I didn’t know if they ever got darker than that. I have had my blood hcg tested and on 9dpo it was only 19 and 12 dpo it was 224. By now it’s should be a minimum of 500 but with the way it’s been rising it is probably higher than that.