Your vet suggested 0.44 mg/kg, which is in the normal range.
Minimum effective dose is said to be 0.2 mg/kg (this is also the most common one in vet formularies)
Max dose, which is the one I use, is 1 mg/kg.
If you want to follow his directions, give 0.02 ml per pound of bodyweight. If you want to use the max dose, use 0.045 ml per pound of body weight (okay to round up to 0.05 ml per pound).
With your vets suggestion a five pounder would get 0.1 ml
My mega-max dose a five pounder would get 0.227 ml (round up to 0.23 or 0.25)
Does that help at all?