Pregnancy spells don't make you pregnant, they help increase the chances, you still have to, you know, bump uglies, to have one. Try figuring out when you ovulat to increase your chances. If you still can't get pregnant, have some tests run, I'm told it's easier to figure out male fertility so maybe check your boyfriend first.
While you work on getting pregnant, perhaps try eliminating unhealthy habits [smoking, alcohol, if any drug use] and try to eat healthy and exercise, wouldn't hurt anyway. Good luck to you.