Well because I hardly feel any difference when I (don't ) wear it.
And my shirt is coming up and my pants is going down

nah really I have to make a really tight nob in it and after using it for a long time it start hurting on my belly area.
It sounds stupid, but my first pair was an under armor one and I didn't have any of the mentioned issues with them.
As I'm thinking of taking up rugbyagain in january untill our cricket season starts I just need a decent baselayer. It's alos awesome for jogging and other sports during summer.