from what you are describing, i would say that your periods are irregular, in that they're not the way they used to be. also the fact that it's only about a year since you stopped taking the pill may mean that your body is still settling down to it's own regular cycle (your natural cycle may be much shorter than the average 28 days). if it was me, i'd give it a few more months and see what happens, it will probably all settle down, but if you're worried then don't hesitate to see your doctor to put your mind at rest.
also, at 39 it could be the first sign of peri-menopause.