If it didn't show up within the time limit of the test, I'd test again with FMU tomorrow. Blue dyes are not supposed to be great after the time limit! This could either be a really nasty evap or the start of something.
Hope you get the result you want and good luck!
Depends how long after, within 30-60 mins I'd say maybe bfp, if it's hours later it'll be evap. But they are conservative with that 15 mins thing, it doesn't mean that any line appearing after that is definitely a false positive, it means that any line appearing within that is a true positive. Aka you can't necessarily trust lines after 15 mins but they might still be true.
Any opinions, advice, statements or other information expressed or made available on BabyandBump.Momtastic.com by users or third parties, including but not limited to bloggers, are solely those of the respective user or other third party. They do not reflect the opinions of BabyandBump.Momtastic.com and they have not been reviewed by a physician, psychologist or parenting expert or any member of the BabyandBump.Momtastic.com staff for accuracy, balance or objectivity. Content and other information presented on BabyandBump.Momtastic.com are not a substitute for professional medical or mental health advice, counseling, diagnosis, or treatment. Never delay or disregard seeking professional medical or mental health advice from your physician or other qualified health provider because of something you have read on BabyandBump.Momtastic.com. BabyandBump.Momtastic.com does not endorse any opinion, advice, statement, product, service or treatment made available on the website. If you think you have a medical emergency, call your doctor or emergency services immediately.