Is my Parakeet EXPECTING?

okay, i have a male and female parakeet. from the beginning (couple months ago) they've always been super close. ive seen them clean each other, sing to each other. ive seen the male get really excited when ive had them separated. But as far as i can tell ive never seen any signs of them mating. When i got the female the person at the petstore said they would only mate in a breading cage ? and that youd see them mate (he pretty much promised me this lol) Anyways, today i took the cage from the window and noticed that the house i bought them 2 months back (with nesting material) that all the nesting material had been thrown from the house to the cage floor in a ball. and there was white feathers every where (from the female) The female has never been an active bird, thats why its weird to wake up to this lol. anyways my only other question is could she be expecting? im not really sure, like what are some signs of her being preg. also if being pregnant is NOT the case, then why was all the nesting on the cage floor? thanks in advance.