Ovulation cramps do exist.

It is not possible for us to say when you ovulate as every woman is different.

Ovulation is when the ovary (usually only one at a time) releases the egg that has matured.

A menstrual cycle consists of the follicular phase (this is controlled by the hormone estrogen) and is when the egg folicle ripens. This phase can vary a lot between women and in the same woman. (a typical 28 day cycle put this phase at 14 days also, but a follicular phase is commonly between 10 and 30 days). Menses overlaps the follicular phase.
Then ovulation occurs, which is the release of the egg. This is where progesterone takes over.
Then the luteal phase begins. It is approximately 14 days, and at the end of the luteal phase you get your period.
It is unusual for the luteal phase to differ much between women with 12-16 days being the norm, although 8-20 is also within the range of normal.
It is very uncommon for the luteal phase to change within the same woman by more than a day or so.

(over the course of 2/3 years mine has changed from 13 days to 14 and gradually on to about 15/16 and I think a lot of it has to do with my age and physical situation)

the egg, once released from the ovary, is viable for upto 36 hours.
Sperm can survive inside the fertile female for around 5 days.
So your window of "high fertility" is from 5 days before until the day after ovulation.

Does that help?