I would say that +/- 5% of fill is not really an underfill for the representative sample, and care MUCH more about the purity of the product (which I think the lowest was like 98.9%, and it was 1 vial maybe out of 22 or something, most were in the 99.5% range.
I have been using my AmoPure stash for 2 months now with no change vs. compounded, I treat each vial as 60mg, regardless of the 1 or 2 mg our test showed it was lower by. Natural variation is normal in manufacturing processes, and I wouldn't be surprised at all if most compounding have a range of +/- 2-4% variations in fills.
You can also mix 2 vials together to most likely get closer the representative sample if you get it tested.
There are many independent tests YOU can do to see if your body chemistry is playing a role in how you are feeling, take a few weeks off of all tirz and start back at 2.5mg.
You may also have a unique reaction (stinging) to the medication based on a specific chemical in their fillers that others don't actually experience.
For example, I ordered the "Pegasus" formula from Kimera because I heard good things about the energy benefits because I was experiencing some lethargy on my 7.5mg dose of Tirz. Guess what? Crazy stinging, painful site reaction, and not much energy benefit.... My significant other? No stinging, definitely felt some energy benefit. Does that mean that was a bad product, or does it mean my body doesn't play kindly with that formulation, seems to be the latter...