1 unit may no longer be safe for Camille tomorrow. Here's why: You had low numbers today in the 60's if I am remembering correctly, and 12 hours after you gave the shot, Camille's BG level is 93. That is a non-diabetic number. You are using the Alpha Trak meter which typically runs higher than the human meters most of us use. So your low today of 60 could have been, say 30 or 40 by comparison -- which could have been a hypo situation for Camille (even though she didn't have symptoms). From what I have learned, once a cat goes into hypo numbers, it can become very sensitive to insulin and some even (miraculously) do not need insulin at all anymore. I saw that happen here on this board within the last month (cat named Thomas).
Not to say that this will happen for Camille, but you can't assume - without knowing her pre-shot reading tomorrow -- that 1 unit will be safe. Her pre-shot BG may be within normal non-diabetic range, or only slightly elevated -- in which case 1 unit could send her into the same roller coaster ride you experienced today. Even if her BG reading is high, 1 unit may not work. Sometimes high numbers, after a day of very lows, is the cat's body trying dumping glucose into the system to combat the hypo and is not indicative of "real" BG numbers. Then again, 1 unit may be fine tomorrow. It all depends.
This is a complicated dance to learn, and if you start the insulin at too high a dose, you set into motion this roller coaster effect that you saw today. So I would urge you to test her BG levels in the morning and ask for input on dosing from the more experienced members of this board. They have saved the lives of hundreds if not thousands of cats and will give you good, cautious advice based upon years of experience.
I am so sorry your first day was so hectic and stressful. It is not typically this way. There is a lot of great information on this board, and great people who will help you if you ask. I am hoping the more experienced members will weigh in on the above info to make sure I am telling you correctly. Also, I know it is instinctive to want to trust the advice of your vet above all else, but with all due respect, your vet recommended the 2 unit dose today that proved too much for Camille. Couldn't hurt to get a second opinion from the experienced folks on this board. They all work with their vets on this too, so you are getting the collective wisdom and experience of a lot of people here.
PS: Camille is beautiful!!!!