psychology question / small stakes loser

I've been playing poker for about a year and a half now. I have read over 15 poker books and do constant thinking about the game. But somehow I during this past year and a half I have been a loser in poker. I feel that part of my problem is that when I play poker I get really caught up with the money factor and play scare poker. In essence I'm not playing my A game because I'm afraid to lose. For example sometimes I have a hard time calling a potential bluffer even when I know I probably have the best hand. I'm sick of playing scare and don't know how I can get over this problem. Hope some of you can give me some advice on this matter.