Sometimes I really regret my decisions.
regret is a negative emotion where you feel bad for doing something
Yeah exactly, sometimes I just think I could've done better.
regret is also related to percieved oppurtunity
That makes a lot of sense, a lot could be gained from doing things right.
Regret
Regret is a negative conscious and emotional reaction to an undesirable situation. 
Regret is related to perceived opportunity. Its intensity varies over time after the decision, in regard to action versus inaction, and in regard to self-control at a particular age. The self-recrimination which comes with regret is thought to spur corrective action and adaptation. 
In Western societies adults have the highest regrets regarding choices of their education. 
Definition.
Regret has been defined by psychologists in the late 1990s as a "
different name [laughs]. It really didn't make much sense now that I think about it, it's like 'Damn, I easily could've called this something else and let be its own thing,' because I feel like I unintentionally alienated a lot of my fans that just wanted to hear what I normally do as Prefuse. That, for me, is my biggest regret about it. It's not that I regret the music, I just should have catalogued it differently."
Reception.