There is a tradition in Orthodox (not Conservative) to keep niddah like a zava- meaning 4-5 bleeding days and then 7 additional clean days. In the Torah, niddda is 7 days and then mikveh. This was the way it was until the expulsion of the Jewish people when it was felt that people would get confused with the counting for niddah. My question is if the woman went to mikveh after the 7 days, is it ok bedieved? Thanks.
If the woman did a "hefsek taharah" (meaning she checked herself and was clean) before immersing the Mikva, then M'Doriasa (according to Biblical law), she is okay. But according to rabbinic law, she is still a niddah until she counts seven clean days and then immerses.