It could be. Do you do the basil body temperature test. That is what we used in reverse to avoid pregnancy, and later to achieve pregnancy.

Using a digital thermometer by your bed. Take your temp (by mouth) and record the temperature. Do not get out of bed. Do that before you rise. Just reach over and grab it. Any way record the temp from every morning. Soon you will see a pattern of days that your temperature is just a few tenths of a degree higher. ex 98.7 normal. 99.0 ovulating or 98.9 ovulating. But you need to get a good baseline for your own body temp. That is the least expensive way to check and see.