Hi Jenn,
You've had quite a day! I wanted to give you some info about your questions.
On this post
Where Can I Find?" (you may want to bookmark it) if you look in the second half there is a link to a post with a recent discussion about Slippery Elm Bark.
For your syringes, consistency is important, so use the same brand as much as you can. You might want to use calipers to help with accurate dosing, or you can use a sample syringe with colored water/tea in it, or masking tape marking the dose you want, and then use it to draw up a dose and disregard the markings on the syringes. In that same post above, there is a post on "dosing with calipers" that discusses the syringe marking inaccuracies.
The huge drop tonight from pmps to +2 - that is fast enough that it's likely to cause a bounce. Next time you see a big drop like that, try to feed some regular low carb to slow it down.
Regarding your question about why he would be dropping so low today - has anyone told you that in cats, the potential exists for the pancreas to heal and for the cat to become diet-controlled? It doesn't happen to every cat, of course, but if it's possible, getting the cat into normal blood sugar range and keeping them there as soon as possible after diagnosis - what the Tight Regulation Protocol is based upon - allows the cat's pancreas to heal, if possible.
When I see that he's clearing any bounce from today's 40's and he's already back in blue numbers by tonight, that tells me that his body has been in normal numbers enough that the bounce isn't big and isn't lasting long. You may have low numbers again tonight. It's possible he's still in a bounce tonight - when cats are bouncing they don't stay 400-400-400 for 12 hours, it can go high and bobble around up and down for as long a 3 days, depending on the cat. If he keeps going higher tonight, that'll tell you it's still a bounce. If he starts coming back down, then you'll have to keep monitoring.
He also might have gone lower today because of diet changes. The raw food that you're giving him - is that a change or has he been eating like that for a while? Raw food is very low carb and low carb needs less insulin than higher carbs.
Hope that's not all overwhelming to you - i just hadn't seen those particular questions addressed yet.