Let me try that again, u/taliesin12.
This is BYU's Corpus tool:
https://www.lds-general-conference.org/
The Corpus tool is a searchable index of General Conference talks from 1851-the present.
A few minutes, I used it to look up "Heavenly Mother" (5 mentions), "Mother in Heaven" (28 mentions), "Heavenly Parents" (120 mentions). I'm sure a clever person could squeeze out a few more references if they worked at it for a while.
You also have a set of references collated in a Gospel Topic article:
https://www.churchofjesuschrist.org/study/manual/gospel-topics-essays/mother-in-heaven?lang=eng
that links to 13 statements/references.
Additionally, Heavenly Mother is mentioned in three statements issued by the first presidency.
Wikipedia's article on Heavenly Mother here:
https://en.wikipedia.org/wiki/Heavenly_Mother_(Mormonism)#cite_note-Paulsen_&_Pulido_2011-26
lists 43 additional references to books, magazine articles, speeches, hymns/poems where highly visible members of the LDS Church talk about her.
BYU Studies has 12 references to HM:
https://byustudies.byu.edu/search-results?search_api_views_fulltext=+heavenly+mother
Sunstone has 77:
https://www.sunstonemagazine.com/?s=heavenly+mother
Dialogue has 90:
https://www.dialoguejournal.com/?s=heavenly+mother
You can find lots and lots more looking through unindexed back issues here:
https://byustudies.byu.edu/all-journals
and here:
https://www.sunstonemagazine.com/magazine/
and here:
https://www.dialoguejournal.com/explore/full-issues/
In 21 minutes I found 391 references to Heavenly Mother (not including 100's of blogs/podcasts and GC talks from 1830-1851). Get back to me when you've worked through those references. I'm interested in your feedback on them.