Clicking on your own profile will list your recent postings.
On rare occasions messages are deleted if considered inappropriate, may I ask if any of the messages could be?
A refresh of the screen will show messages they have just been posted.
If you wish to see all the post you have participated, click on the your account name in your avatar.
It should take to the same as this http://community.giffgaff.com/t5/user/viewprofilepage/user-id/3199234