This is just info I am throwing out there. If anyone doesn't like it, then ignore it.
I have had a few monitors over the years, and I have never had one that only ate 3 crickets. Even a six inch Savanna I had would eat many more crickets each day. Small monitors like yours that I have had eat many many crickets or pinkies/fuzzies/hoppers.
The blackthroat I have was 24 inches long a month ago and eats 3 or 4 mice a day. I filled her up once with crickets and 4 or 5 mice (I dont remember which.) She constantly craps. I clean poop out the cage every day, sometimes numerouse times a day. She is doing great, putting on weight, and growing like a weed.
I keep the basking spot 130 degrees or more. The heat helps with digestion. If it takes days to digest and the blackthroat turns down food you may need to check the basking temperature with a heat gun. Blackthroats are not known to turn down food. Especially if they havent eaten in a day or two.
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Ed
These heat lamps make my electric bill to high.