07/07/2009 AT 02:00 PM EDT
is a perfectionist in all areas of her profession, something the Spanish-born star admits she carries over into her personal life.
"Every time I make a film, I feel like it's my first time ... I always think they could fire me," the Oscar winner, 35, tells the August issue of Psychologies
magazine in the U.K. "I've ruined my own happiness and created problems with my friends because of this tendency. It takes discipline for me to stop worrying."
She adds, "I have a tendency to become a mother to everyone around me. My brother and sister are always complaining that I'm too protective."
Someday that might just come in handy. Currently linked to fellow Spaniard Javier Bardem – about whom Cruz would only say, "He's a wonderful man, a great actor" – she does admit that she definitely desires kids.
"I want to have babies one day but not right now. When I do it I want to do it really well. I want it to be my best project in life," says Cruz. "I don’t know if I believe in marriage. I believe in family, love and children."
Appropriately enough, Cruz's next film is kid-friendly. She voices a gerbil spy named Juarez in Disney's G-Force
, which hits theaters July 31.