constantly getting shadow lines on FRER

as most of you probably know...FRER has changed their strips where it picks up the faintest of lines so its common to get faint line even when you are not pregnant. But i live in Canada so the new FRERs dont apply here yet so they are the same reliable tests.

I took a FRER at 8DPO in the evening of the 29th of march and got a faint bfp. it was a light pink line then faded after about 15-20 minutes to a shadow line but still there. then yesterday i took 4 FRER test and the same thing happened with all of them. took 2 this morning and it did the same thing with the first one but the second one i held my pee in for 3 hours and was completely neg. i also took a CB yesterday and dollar tests and they were neg as well. It doesnt make sense that they would be nice pink lines and turn into shadow lines after 20 minutes.
Ive never had evaps on FRER before. later this evening i took a CB test an got a VERY faint line on that as well that was able to pick up in a picture as well but still one of those questionable lines that you're not sure if you're eyes are playing tricks on you or not.

so i am COMPLETELY confused! Im 10 DPO today. Has anyone had so many shadow lines on FRER before??