you are right you aren't meant to take them when actively ttc, they do stay in your system for a while, not sure how long from memory, i think maybe you get the effect from them for 6 weeks, having said that i take them on a weekly basis (what dose are you on ?) i haven't ever really had too many side effects from them......and have conceived while still on them.

my prolactin was around 1200 when i started them, i successfully bf my DD for 15 months and seemed to have a good milk supply but during my pregnancy with her my prolactin went really high and i developed a pituitary tumour that haemorrhaged at 30 weeks pregnant.
with my son that didn't happen and i didn't feel my milk supply was as good that time because i'd say my prolactin wasn't as high