Hi Amber, I got your email. Ironically we are nursing a female rescue that is about the same condition and size as Ruby Sprinkles. So far everything you are doing is good, especially rehydrating her and gradually letting her get used to real food, mainly protein. I always start with water and electrolytes for a few days, then add greens and butternut baby food before moving on to repti-boost and chicken.
The Flukers Repti-boost is a good way to wean her back on protein because it contains egg protein which is well tolerated and easy to digest. Yes the directions are not very specific, so you can estimate with the 1% of total body weight per day like the daily fluid requirements. That scoop is super tiny and won't even make 1cc mixed 50/50 with water, you can use 1/4 or 1/2 teaspoon and mix it with butternut baby food or water to make up however much you need to make up a feeding. So a 100 gram dragon should eat approximately 10cc per day split up into 2 or 3 feedings. If she is eating 2 to 4 cc's at a time, then that's just right. I usually use this before the chicken baby food or mix it all together.
Since you are using a liquid calcium that has a higher bioavailability than the powdered calcium carbonate, then you don't really need to use D3. Calcium carbonate is more for dusting bugs because it acts as a phosphorus binder and helps remove the excess phosphorus contained in bugs exoskeletons. Calcium carbonate has the lowest bioavailability of all calciums, therefore usualy needs D3 to make it useful as a supplement. Most liquid calciums are made from calcium salts that are more readily absorbed and the D3 made from good UVB exposure is usually sufficient. In some cases when a dragon is suffering from severe mbd symptoms, then I would recommend some D3 in with the liquid for a couple weeks to start out their therapy. She doesn't seem to need it badly, so wait till she starts eating more bugs, then you can dust with a calcium powder fortified with D3.
About the poop that was dryish on the inside, this is usually normal of dragons that haven't pooped in a very long time and are dehydrated. You will see poop like this when dragons wake up from long periods of brumation, so that tells me she hasn't eaten or pooped in probably a good month or two.
When we first got our rescue back on live feeders, we would go through and pick out the white freshly shed dubia and give her a couple small ones at a time. Every time we fed her, we would give her a couple more until we knew she was tolerating them well. After about 3 weeks, her appetite has gone out of control and she will eat 5x more than normal. It seems slow at first, but you'll know when she's ready to go to the next step. Their activity levels increase, they jump at the chance to eat every time you pass the cage and it's like a total transformation. Email me anytime if you have questions.
Cheryl