Has anyone else ever had test like this?? HELP

Has anyone ever had a faint pos then take a test the next day and nothing?? Has anyone ended up prego? I can't get a false pos right?? Maybe my hcg is low? Or chemical? I'm 15 dpo! Please any help would be great!!  
3/9 is my vf  and the one with the ring is my neg.. I think..