Tested using the other FRER this morning and it came up negative. Done another internet cheapie and it's come up with another very faint line but no stronger than it was a couple of days ago so looks like it's a BFN for me for now
It's really awkward though as I have no idea where to date myself from as I haven't had any bleed since stopping the pill yet so guess I'll just have to bulk up on cheap tests and keep testing every couple of days until AF does (or hopefully doesn't 🤞) come