Home sizes have been increasing over the years. This article talks about that: http://tinyurl.com/555cde (you can search on google for "average home size" + "increasing" to find more)
I had two sisters and we shared one large bedroom while growing up and it was fun. Every family I grew up with that had multiple children had them sharing rooms at some point. My daughter will be sharing a room with her sister (if we have another daughter!).
Look in real estate listings at home built prior to the 80s and homes built after the 90s. There is a huge difference (pun sort of intended) in square footage.
I think your boys will be just fine sharing a room. You're moving into the apartment for the benefit of the family. Yes, it would be nice if they could have their own rooms, but it would be better for everyone if your family was financially stable - that alone eliminates LOTS of stress.
Your boys deserve enough food to eat, a roof over their head, clothing, and some fun. You're providing that well. People are always happy to be telling you what you're doing wrong as a parent, but I'm telling you you're doing something right. And besides, your coworkers probably have no problem about two people sharing a dorm room which is essentially the same thing, only they're sharing the room with family and not a stranger.
Good luck. You're doing fine. :) Sorry for being long-winded. I feel a bit strongly about this apparently (ha).