Feeling cramped!

[Tink]

My 21 yr old son and 19 yr old daughter have both moved back home. They each have a "sweetie" who they bring over often. A young man who has been like a son to us for several years (and is close friends with both of the kids) is currently staying with us, plus of course Dh and I, Moses, Canada, the 12 puppies, and our cat all live here. This is a small 2 bedroom house we bought with "empty nest retirement years" in mind. It's less than 1000 sq ft!

To say we're cramped is an understatment!
We have one bathroom... NIGHTMARE trying to get a shower!
Our living room is overflowing with people all wanting to watch/do different things at the same time.
Our garage is full of all the STUFF they dragged home with them.
DH and I feel we're being pressed right out of our own home.

SO something's got to be done. How much time is ENOUGH time to give them all to get on their feet and fly the coop?
What's a reasonable amount to expect them all to kick in for expenses in the meantime? We're going broke feeding them all, and paying for all the extras that keeping them involves!
I don't mind helping out, but am really sick of tripping over people and their STUFF.
I want my privacy and sanity back but don't want to make enemies in the process.
HELP!