2 faint lines then 2 negatives? Afraid to test again😥😢

Gina • FND Fighter ✊ Narcissistic Abuse Survivor 🤐 Jesus Follower 📖

At 13dpo I took a test on a first response on fmu and got a very very faint line:

I tested again days later with a clear blue test and got a negative...

And then this morning I tested on a first signal and got another negative:

I don't understand. I don't think I'm hanging a chemical because this is day two of missed period. Does this have anything to do with the sensitivity? I've read up some about the sensitivity of each test brands and found the first response has the lowest sensitivity.

Wouldn't my HCG be able to double by now though? I am now 16dpo and afraid to test again until next week..

I also don't have the money to buy more first response. All I have left is clear blue and first signal which is why I used them.