WHY don't MY chickens lay the LARGE eggs? :(

First, thanks for reading!
We have 2 chickens from 2010 raising, (a leghorn and a RIR) and then 4 from raising in 2011 (2 leghorns, 2 black australorps), and even though ALL LAY, they are all (still) SMALL eggs!!!! We have "adopted" 4 other chickens from freecycle.org and "saved" them, and I know for a fact that they were NOT fed well and were CAGED the whole time. 2 of THOSE chickens are not quite a year old, and the other 2 are OLD, like 3-4 years old, BUT they ALL lay these HUGE Eggs!!!!!

What gives??? I'm not kidding, OUR chickens have had the BEST of everything---and they are FREE RANGE in our suburban backyard, with plenty of daily fresh water, nesting grass/chips, a warm, roomy coop with a heat lamp, Chick starter feed, then layer feed with 22% protein, and scraps from us almost daily.

I'm sorry, I'm just frustrated, A. because they don't always lay every day of course (we thought those black austrolorps were supposed to be good layers like the RIR and white Leghorns) and B. because these eggs are so puny---when I bake I have to add an "extra" egg in because they are probably less then/about a "medium" size.

Any ideas WHAT I could possibly be doing wrong? We love the chickens, we like raising them with our kids, but I just want large eggs like the "adopted" ones (we have to give 2 of them back to our neighbor in Spring, and the Freecycle 2 don't lay every day---maybe 3 times a week) So.......we're not getting many in the first place and we have to give a couple back soon.

I just want those large eggs from OUR birds, that are the same as those other ill-kept ones

 

Oh, I should add (I don't think I did?) that the 2 ones that are less than a year old are a black austrolorp and a RIR, and the 2 older freecycle ones are both RIR.

 

Thanks, I just know that the OTHER 2 that are pullets (actually from a neighbor that we have to give back this Spring) ALSO are young, yet I know that they are the ones laying these huge brown eggs (they lay in a corner on the floor instead of the nesting boxes) and have laid every day for us since we got them 2 weeks ago......so, I just don't get why my 4 young ones (and then my 2 almost 2-year-olds) are STILL laying these small size eggs. I also forgot to add we put oyster shell in the feed so that is there as well......... I would never not feed our chickens well, nor keep them in the coop all day (unless it was nasty weather) so I again just don't understand why I'm not getting the best eggs we can? Granted, they ARE fresh and we enjoy the chickens like pets, but i feel like they are letting me down!

 

You all are awesome to read my vent and answer Thank you!
I will enjoy what we have for now and hope for bigger (maybe) in the future

I also have to add (for sympathy) that a 2010 leghorn we raised was AWESOME and gave us a DOUBLE yolk at least 2x a week (her poor bum!) and laid every day large white eggs! Sadly, when she was not quite a year old, some animal got to her through our back fence (we still have no idea how it happened, sneaky animal!) and she was killed I miss her!