Why do my girls lay small eggs?

[CluckerCottage]

As long as they are getting the proper nutrition, no need to worry-- their eggs will improve in size.
My BO's are 21 weeks and their eggs are still tiny. Great omelets! They have been laying for 2-3 weeks now.
My SLW's eggs are the same size. My WL's are giving me medium eggs but they have been laying for over a month now.
I am sorry that your SLW's are picking on your BO's but honestly, BO's are so docile that they usually DO end up at the bottom of the pecking order.
It's the same here in my mixed flock. I have never seen anything bad (no blood drawn or anything) just a quick peck or lunge towards the BO's, mainly when I toss them treats.
Normal chicken behavior.

 

[GC-Raptor]

It also depends on the breed. My golden comets first eggs were 42-43grams. After 4 to 5 weeks, they range from about 54 to 61grams. Sometimes smaller, sometimes bigger. But I've gotten double yoke's at 71 and 84grams

This was one day, 2 medium, 1 large, 1 EL and 1 84 grams Extra Jumbo. GC