What you are experiencing is why most folks raise certain types of chickes for eggs and other types for meat and why commercial egg farmers don't bother raising the cockrels of egg laying breeds at all. As redsox suggested, you might want to look at dual purpose breeds like Brahmas or Buff Orphigtons. They may not lay quite as dependably as the best layers or put on meat as quickly and cheaply as the Cornish X or Freedom Rangers, but if you want to contiue to hatch batches of fertile eggs from your own and keep the females for layers and process the males for the dinner table, you might have better results.
So far I've raised one group of chicks as layers (WPR, BPR, EE, Jersey Giant, Welsummer) for eggs and a second group of chicks, all Freedom Rangers, for meat. It was amazing how much more quickly the Freedom Rangers started feathering out and how large they were by 9 or 10 weeks. It is my understanding that the Cornish X grow even faster, but I had concerns with their health and decided I'd rather wait a week or two for the Freedom Rangers. I thought I'd keep several of the pullets and one of the roosters to see if I could do what you do, hatch out a few batches of eggs in the spring, but ended up butchering the rooster because he was a bully and was injuring the hens. So, if I want to do meat birds again I'll need to start with day old chicks.