We are sorry to hear of your blighted ovum and of your prolonged time spent in niddah.
Bleeding following miscarriage can resemble postpartum bleeding, which can be prolonged and can come and go in waves. So it is possible that the spotting will continue.
On a halachic level, the most important step you can take is to review the laws of stains, as by reading our site’s articles “Ketamim” and “Toilet Paper“. A woman can sometimes become tehorah even when staining is ongoing. Not all stains invalidate the clean days. Furthermore, not all bedikot need be clear; some browns may be acceptable even on a hefsek taharah.
After reviewing the laws of stains, we suggest that you attempt to make a hefsek taharah. For this cycle, you may omit the moch dachuk and do only three bedikot during shivah neki’im: one on day 1, one on day 7, and one on one of the intermediate days. Any questionable bedikah cloths or stains should be brought to a halachic authority for evaluation.
We hope these steps help you reach the mikveh soon. We wish you a refuah sheleimah and a sweet new year. Please write back with any further questions.