For the forum, in the top right corner, click your profile picture, then the person icon, then Activity:
On the left side of the page, click Replies:
https://forum.inaturalist.org/u/shecoyote/activity/replies
(On the off chance you might also be referring to replies/comments on iNaturalist observations, you can go to https://www.inaturalist.org/comments?mine=true to see your comments on observations. It won’t include your comments attached to IDs though.)