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How is your cycle?
At how many days' interval do you get period?
The chances of getting pregnancy increases when you have sex during ovulation.
Ovulation usually occurs around 12 - 14 days before the next estimated date of period.
But it can vary from cycle to cycle.
However, it nearly occurs from day 11 to day 21 of the cycle in most cases.
So you can try to track your ovulation.
Does she get regular period like every 28 days?
How many days' does it last? Do you know her menstrual history in details?