J.A.
I also make all of my baby's food at home and use the same book to guide me. I was able to overcome the gumminess with some practice. You may be cooking it for too long, or the heat may be too high for it. You just have to play with it until you finally get it. I also refrain from freezing it. It definitely gets gummier after freezing. You can also try to add some more water, formula or breast milk before putting it in the microwave. I usually add some water before putting it in the microwave, then once it's warm I add a little breast milk, so that it has a smoother texture. Hope it works!