You need a LOT more info than that to even make an educated guess.

As smoothy said, more information is needed. The length of your period doesn't matter. Generally women will ovulate about 12-16 days before the next period is due no matter how long their cycle or their periods are. That is only a starting place however, and it is not exact for everyone. If cycles are irregular, it would be different still just due to the irregularity.