“Motchi” is a male name.
The Hebrew male name ‘Mordechai' is commonly pronounced by Yiddish speakers as ‘Mordcha' or Mordcheh.”’
If the subject in question is female, there is a similar sounding female name to the nickname of Mordechai. The female Yiddish name ‘Mattl’ (pronounced ‘Mahtl) sounds similar to the male name “Mottl.” (But “Motchi” would not be used for a female)
Hope this helps explains the confusion of gender.
Avrohom Krauss
Telz-Stone Israel