Try to start charting your temps, cm, and cp. You could also try an ovualtion predictor kit. We have no crystal balls so we cannot tell when you are going to ovulate. It is usually 14 days before your period.

It looks like last month you had a 25 day cycle, so you most likely ovulated about 11 days after the start of your period. Are your periods normally early or do they vary from month to month? If this is normal for you then you will probably ovulate somewhere around the 18th this month. Hope this helps.

Your periods aren't measured by calendar months.

Just because you get it one the 17th one month doesn't mean it'll be the 17th the following month.

The first day of bleeding is day 1 then you count until the start of the next period and that is the number of days in your cycle.

This can vary from woman to woman and cycle to cycle (although not usually much betwen cycles unless you have an irregular cycle).

Even knowing the length of your cycle doesn't mean you will know when you ovulate.

You'd need to be a dedicated charter of temps/cm/dates/cervix/etc to be able to make an educated guess on that.

However, the average works out that you ovulate 14 days before your period. So, if you have a regular 28 day cycle you are likely to ovulate around day 14. If you have a 35 day cycle you are likely to ovulate around day 21.
But again it is not possible to say for sure.