How many times are you bf'ing your lo? By now, your body is well-adjusted to making the amount of milk that you are feeding your lo, so feeling full is not likely to happen very much (unless there is a sudden decrease in the amount you are feeding). It is also common to not feel let-down after a while (I can't remember when, but with dd1 there was a point where I no longer felt let-down, and some women never feel the let-down). Also, the amount of time on the breast is not really an indication of how much your lo is getting - as they get older they do get more efficient. My dd1 was only nursing for that length of time at that age. Does your lo seem satisfied after nursing?
Having said that, I know some mothers do notice a decrease in supply if they're only feeding once or twice per day.