(entertainmentwise.com) - Angelina Jolie is reportedly feeling the strain following the birth of twins Know & Vivienne.Whilst partner Brad Pitt is described as a "punch-drunk, happy-tired" new daddy, the actress is said to be finding the two new additions to the ever-expanding Jolie-Pitt clan harder to handle."(The family's French home is) frantic and messy. There are toys and clothes strewn in practically every room," a source tells In Touch.But it's "feeding the twins on demand" that is really taking it's toll, according to insiders."Angie is tired all the time," says another source. "Knox wakes up, and (she) will spend an hour feeding and then changing him, and then Viv wakes up as Knox is going to sleep. "Then, by the time Angelina has fed and changed Viv, she has about 10 minutes to sleep before it all starts over again." Despite being completely worn out, the source adds that Angelina "wouldn't trade being a mother for anything else in the world."