I did a HPT every day from 5DPT just to test when the booster would be out of my system! lol everyday i got a BFP lighter, stronger, then lighter again this went on until my BT which turned out to be positive but MC. so i cant answer your question with regards to whether this is a true BFP or booster still
I have however read someladies say it can take up to a week, others calculate it at a loss of 1000 a day so if your last injection was 5000 iu then it will take at least 5 days to leave your system
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