Is always better to err on the side of caution when you can't be around to monitor; so don't worry, you're doing fine!
I don't know what your work schedule is, but I'd recommend that if/when you decide to bump up Sam's dose a little, you do it gradually - in increment of no more than 0.25U and ONLY if you're going to be around to test during that cycle. (Maybe that would be over a weekend?)
Which syringe are you using - the u40 (which is standard issue for ProZinc) or the U10o? As you can get U100 syringes - capacity 3/10 mL(cc) - marked on the half-unit and use our conversion table for dosing, which makes it a lot easier to do small dosage adjustments with ProZinc.