how long have you been on the Paleo diet?

I have tried
Pale Diet, Feingold diet, Anti-candida diet, No Carb Diet, GI Diet, Atkins diet and pretty much every different method of avoiding things most people are allergic too. I have been somewhat unhappy and depressed the whole time during the diet as I cant lead a normal life with friends and family. Concious of what I am eating frustrates me.

How long did it take before you see improvements? and how do you know which diet is for who? I tried them all for over 2 monthes and failed.