You can simply go to your profile, go to the activity tab and click on "n helpful flags". (On the right side, grouped together with the stats such as "people reached", "votes cast" and "posts edited".)
You will get to the list of your flags, you can then sort them by categories (post flags, comment flags, spam flags). You can see whether the flags have been marked helpful or declined. And if there was some response from the moderator handling the flag, the response will be displayed here, too.
Your flag history is visible to yourself - other regular users do not have access to the list of your flags.
See also:
- The tag-info for flagging-history on Meta Stack Exchange.
- Meta Stack Exchange: Where can I see my flag count / history? and How can I review my flags?