A woman must perform at least one bedikah on the first day of the shivah nekiim. In this case, your Sunday bedikah can be considered your hefsek taharah, and a bedikah today (Tuesday), would enable you to count Tuesday as your first day. If all goes well, you can then go to the mikveh Monday night, which we hope will still be before ovulation.
To avoid this problem in the future, we recommend performing a bedikah on any day that might turn out to be the first of your shivah neki’im – even if you have been told to check only on the first and last days. In this case, you would have done one bedikah on Monday just in case the moch turned out not to be good. That would have allowed you to count Monday as the first of the shivah neki’im.
Please also ask your rabbi whether you should continue to use the moch at this time. Often, when a rabbi suggests reducing the number of bedikot, he also recommends omitting the moch.
If you are using Clomid to push off ovulation, you also may find it helpful to read our site’s article on ovulating before immersion and even to arrange a free consultation with a Yoetzet Halacha Fertility Counselor, details here.
B’hatzlacha!
This response was updated on 4 May, 2021.