I am so confused, someone help clarify?!

On Feb 11th I had a chemical miscarriage at 2 weeks pregnant, hcg was 9 then 2 then 4. A day after I went and got the 2 levels, all tests were negative. I had the bleeding and it was really mucousy. The bleeding stopped Feb16th. Hubby and I immediately had sex day after. On Feb 27th i had stretchy mucus, and took a test three days ago and it was negative, just because I bought a huge pack and dont know why else lol.

Last night I took one again out of curiosity and it was super barely there...today I took two with fmu and then later and I could see very faintly again, of course within time limit and with color but camera couldnt see it 💁 so i went to edit and change lighting and low and behold, clear as day!

Why would I all of a sudden at 4 dpo possibly unless it was earlier, get a very faint positive when hcg went to 0 several weeks ago?

Also these test 25 units and before with chemical i only got positives on early response, negative on drs besides blood beta due to not going past 10 units!