If you drain your own energy, yes, you could feel tired or sick.
Fertility spells making you feel pregnant is a maybe. If you are trying to get pregnant with your boyfriend or through other means then maybe as it increases the chances of pregnancy, but it won't instantly make you pregnant simply because you cast the spell. Have some tests run by the doctor, some woman who want kids badly, sometimes can trick the mind into thinking they are pregnant and they can physically feel the symptoms. I don't know if a urine test would work [probably not because your body is producing the hormones the test would be checking for hense a doctor's checkup] but go for some tests to be sure. Until you get the answer of course, cut out anything harmful to your pregnancy just to be safe.