parakeet babies possibly?

i think our parakeets may be thinking about parenthood.
those weak baby tweets that our girl was making, i think it's just part of mating.  as she sat on my finger a bit ago i noticed how heavy she felt and how warm her feet were on me. 
last week we thought that maybe she was "egg bound" and wanting a nesting box so i wood glued together a little birdhouse craft that was left over from christmas presents.  i put it in there and now the girl is in there alot.  their neres are becoming darker.  sprite- the boy, he used to be so mild mannered and nice.  he now has a pretty fierce bite.  whereas kite- the girl, she used to be the cage defender, fierce and always sticking up for sprite when the little kids would bother them.  now she sits back and lets sprite defend. 
and one more thing is their appetite is crazy.  they used to only eat seed.  millet preferably from their mix.  and whenever i offered lettuce or berries they'd be scared of it.  so to help kite not be egg bound i started offering greens again. they eat the greens like we've been starving them. 
also, sprite- his song has always been fancy and show-offy.  you can almost see kite rolling her eyes.  it's hilarious watching her fall asleep while he's showing off.  anyway, his song is WAY more show-offy.  he's got all these whistles i've never heard before. 
i'm kind of getting excited.  the kids want to check the nest box every day for an egg.  but i keep telling them that kite would be sitting on them constantly if there was an egg there.