is usually done for some skin manifestations, if it is so it wont cause any complication with reproduction.
Micronor contains norethisterone
is used as birth control or to regulate bleeding.
Usually stopping this can cause breakthrough bleeding
It also sometimes cause irregularity in bleeding.
It will become normal usually in one or two months.
Since your UPT is negative there is possibly no question of pregnancy
If irregularity continues you should consult your Gync for advice