I'll just add a few comments here to help re-assure you since I have a small AT in Quarantine right now as well and ours went in about the same time.
The fish I received was about the same size as yours, but didn't look nearly as nice when it came in. For a period of nearly two weeks, it would barely eat and scuffled with bouts of lateral line disease. I ended up replacing every electrical device in the tank to finally get the lateral line to cease.
It has only been in the last week or so that it's finally started to eat any of the floating prepared foods (I feed the LRS foods and PE mysid), it had been subsiding for close to three weeks on the occasional algae nibble.
Additionally, in regards to flukes, when you preformed the FW dip, if flukes had been present, they would have most likely come off in the in first three to five minutes. You can see the fluke start to fill up with FW and appear like a bump on the surface of the fish before it comes off the fish. They can vary in size, depending the age and specie of the flukes. They are about the size of a piece of rice, cut in half generally, and a bit wider. They are also usually an opaque white color.
IMO, if you don't see a lot of flashing or scratching, it's unlikely that there is a fluke issue.
I would continue the full prazi course, as it's only 5 days and then hit the tank with a large water change. Additionally, if you are concerned about flukes after, preform a series of FW dips once the prazi treatment is done. I like to preform them every three days for a period of two weeks or so to be sure that I don't miss the parasite between between it's stages of life. I have only had to do this in the most stubborn of infestations.
To sum up, I think these fish are more resilient than we can be lead to believe a lot of times, if he misses a few meals, he'll be ok. Ensure good water quality, and the correct dose of the prazi and I think your fish will come through treatment just fine.