Well unfortunately I have no idea how to prove it to you beyond the fact that I'm only missing maybe five secret achievements. Ask me and let's see if I've done it or not?
Do you know ... you can having a "free fall" without becoming a dragon yet ?
Do you know ... how to let appear the Amulet of Slantwig ?
Do you know ... finding & killing a Green Chicken you summon a Spider level 22 ?
Do you know ... a dungeon where two sisters are in discussion with eachother ?
Do you know ... the password of the teleporter in Broken Valley, nearby the Chapel Scrine and their is another teleporter too ?
Do you know ... how to open the dungeon that is on the right side of the Chapel in Broken Valley Village ?
Just a small part of the many secrets ...
You really found all the secrets ?
I haven't fount all the achievements, Xbox version and still wonder which secret achievement I have to find, but I believe they're part of the add-on FoV I haven't played much because I always start again in Farglow with another hero
Like I always say:
As long as you've Fun playing a game
You've reason to be happy,
No matter the way You play,
It's of course for nobody the same !