Hi Sally. My GBAs breed fairly constantly too, a brood a month seems to be the average.
I do the same as you, put food outside the males cave, and he always looks healthy and well fed. I've never seen my male eat his eggs. Sometimes the brood is small, sometimes its large, I think that's just the way it goes. Having said that, if yours looks like he's losing weight then it might be a good thing for him to have a couple of weeks rest.
It's best to have more females than males, say 2F to 1M.