The length of your cycle doesn't determine IF you'll ovulate, but it can determine WHEN you ovulate. You may ovulate later than usual this cycle, and you may have some irregularities with your cycle as your body adjusts back to normal hormonally and physically following the recent termination of your pregnancy. If you're charting your cycles, you should be using birth control of some sort if you're having sex at times you're likely to be fertile. Yes, there is a chance of pregnancy if you are near the time you would typically ovulate.
HI,
Ovulation can occur in presence of excessive or scanty bleeding. Hence there can be chances of pregnancy.
Hope this helps.