3 weeks late for af, any input on the hook effect?

Nickie • 28. DH 27. Lost our baby girl at 24 weeks ?Hoping for our rainbow ?
So Af was due the 29th of last month. I have had Sooo many symptoms, such as, increased breast size, Montgomery tubclers, breasts have itched, heartburn, upset stomach, I just noticed I have white stretch marks on the side of my stomach like I have been gaining weight or losing it, or both, increased cm, nausea, headaches, etc.
​I have tested negative on 3 FRERs & unsure on all 5 of my dollar tree tests. The last one I had tweaked on another website, they saw an indent with bits of pink dye. I asked if I should say it's a negative & someone told me to look into the hook effect.
Bascially it's that your body produces too much hcg (and it's very possible to have twins or multiples) & essentially overloads the test. To get an accurate result I've read to use the bathroom & instead of POAS or in a cup, you pee in the toilet & either dip your stick or use whatever method you have.
​I'm going to try this tomorrow morning, I hate that I have no insurance so I can't just get a blood test & my husband & I are going to Mexico in 2 weeks & I want to make sure I'm not pg.
​Anyone have any advice on the hook effect? Thanks