The fun of flexi

Hmmmmm so I always thought working flexi hours could only be a good thing as I can go in when I want (within reason) leave when I want, build up days off, take longer lunches etc etc. Except since December, I have been in negative time on my flexi sheet and can't seem to make it up. I even worked half a day leave on Friday last week!!! I just can't get into credit with it anymore and it sucks. It is like a psychological barrier where I can't get back in credit. Today for example I got up early to go in for an extra hour, looked at my watch which I hadn't put forward on Sunday and thought it was way too early to be getting ready. By the time I realised it was 8:30 which meant the first bus I could take was the 9:15 which only gets me to work at 9:45 which is the latest I am allowed to flex on!!! Even my good intentions pan out badly.