Hi mapvv,
from the look of your games you are playing 5mins +2seconds for every move. If your opponent plays alot of moves quickly they can increase their time very quickly. you can change your time to 5 mins dead without increments by setting the 'bonus'to zero.
Since I started to play from 15 minutes to 5 minutes games in "live chess", i noticed more that, in some games, the time of my opponents is not straight, increases several times the seconds and I think that I´m going to win on time, but I loose.
Happy new Year!!