Can someone explain

So long story short...started spotting 4 days before AF due...thought it could be implantation bleeding. Took a test 2 days later while still getting some heavy spotting and got a faint positive. Next day bleeding started to get heavy so I chopped it up to being a false positive. Yesterday took another test and got a strong positive so I went to the clinic as I was still bleeding. My hcg test came back as only a level of 3. So apparently not pregnant. How could a level of 3 register on any test??? Heartbroken and confused.

First test

Second test