How do you know

How do you know if it’s a positive test or just a faint line or the evaporation line but not actually positive.

I take every precaution possible to avoid pregnancy other then abstinence. Condoms, nexplanon, pullout all together.

Last week, boobs got sore and freaked me out. Officially 9 days ago. Took a first response test this morning and I swear you can see a line but I can’t tell if it’s pink or just the line that usually holds the dye. You can kinda see a line of you really focus, but you can definitely see a line when I hold my phone light up to it but I can’t tell if there is color or not. I’m taking another one tomorrow morning. But, if I had started showing symptoms 9 days ago, then would I have a positive test by now. Like a clear positive. Please help me not stress. I don’t want to be pregnant