It's possible that your body is adjusting to her needs and you won't always feel "full." Also, keep in mind that EASY isn't a tight schedule, but a routine - so don't just feed because the clock says it's been 3.5 hrs. If she's hungry at 3, feed her then. If it's 3 hr 15 min, feed her. The 3.5 hrs is a guideline to how long "most" bubs can go at her age. Many bf bubs do not go as long between feeds as formula fed bubs do. But also, keep in mind that your body does adjust in terms of milk production. As long as she's eating well, producing enough "output" and growing normally, I wouldn't be worried at all about your production.
hth
michelle