Unfortunately, unless you can remove or change the
cast (which may be plausible sooner than three weeks from now), you will have to delay immersion until after the cast is currently scheduled to be removed.
We do recommend observing the
clean days as usual, just in case you find a way to get the cast off for an earlier immersion. No further bathing or
preparations will be necessary until just prior to mikveh immersion. Though you will remain
niddah till after you immerse, you will not need to perform further
bedikot or to continue wearing whites after the seventh clean day.
You may want to consider
pushing off your next menstrual cycle so that you and your husband can have more time together after you do immerse. If you are currently using
combined hormonal contraception, you can extend your cycle by starting a new pack of active pills (or a new ring or patch) without taking a break for the placebos. Otherwise, you can consult your physician about the possibility of taking progesterone to delay your next period.
Please get back to us with any further questions.
Refuah shleimah!