How can you tell if you are pregnant without a test?

Ultrasound: Clinical examination will help. Ultrasound will be definitive if far enough along.

You cannot be sure: There are a lot of symptoms that women can have especially in early pregnancy but these are nonspecific and can easily be attributed to things other than pregnancy as well. Aside from no periods, feeling the baby move, and going into labor, there are very few ways to detect pregnancy in the absence of a pregnancy test.