Two chicks will be fine. As
@Chookchicken said, the usual reason for having three is insurance against losing one.
Quarantine is always a good idea to prevent disease spread. I used to brood chicks in my garage, but in recent years, have simply bought a large plastic tote, topped it with an old window screen and raised them in the house until they are feathered enough to go outside.
I am less concerned about quarantine when I pick up chicks directly from the feed store where they've just arrived from the hatchery. But, I still wouldn't put them in with other birds right away.
If you are adding chicks now, a big tote would be a fairly cheap alternative; tiny chicks don't need a lot of room, and you don't want the older babies picking on the youngsters anyway.
Sorry so many of your babies were boys; better luck with your next chicks!