I have 5' foot female red tail as well she is a sub adult. I was feeding her mediums every sunday (4 times a month) but I had been reading up and everything I read said you wanna feed them a meal large enough to leave a slight bulge. So maybe you should try a couple large rats and see how that goes. As far a feeding schedule goes, I have read that after about 1.5-2years you wanna feed them on a defication schedule. Where as when they are young its best to feed every 7-10 days. These are just what I have read and practice. Snakes seem to do fine with it. For the neonates I like to feed sunday and wednesday, usually smaller meals though.
-Dan
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1.1 Dumerils Boa
1.0 Cali King
1.1.2 Red Tail
0.0.1 Sulcata Tortoise
0.1 Siberian Husky!