Screech

I am 31 years old 6' 4" and about 220. Not really active and feel that have a slow metabolism, often only eating 1 a day. Have not smoked for 21 days and will be tested tomorrow. Prior to that was very hit or mis with my habits, could go 2-4 weeks without then go through a z in 2 weeks. I took a home test today and looks like I failed it. I can see the second line but pretty damn faint. Currently drinking a bunch of water and diet cranberry juice, which i will till tomorrow. I also bought some QCARBO one shot as well today.

With this in mind I have 2 Questions. 1) With home test is any visible line a negative or does it need to be fairly visible? Like I said can see faint line but thought it was from strip getting wet. 2) Does using the QCARBO have any ill effects from using?(Figure since i bought it might as well use it)

Thanks in advance for any advise.