NEGATIVE BETA-HCG but faint line on HPT

I had my frozen embryo transfer May 13th and I am now 9dp5dt of one blast. On Sunday I got a vvvfl on a first response and I have tested everyday since and the line has remained faint but there. Today I took a first response first thing in the morning (posted here) and had my quantitative beta hcg test in the late morning. I will post a pic of my first response but it still has a faint line but my blood test came back as negative at only 3. My clinic wants me to discontinue med support, should I push for another blood test? How is it possible to get a faint line on a test but then a few hours later get a negative blood test. Any one ever experience anything like this? To add since it was a frozen cycle I did not do a trigger shot or anything.