It can be hard to get used to home testing, but I promise it gets easier with practice and it keeps our sugar cats so much safer.
I wanted to add two things. Firstly, I wanted to mention that you don't have to get a pet meter to test Tibby. (cute name!) Most members here use a human meter, like WalMart's ReliOn Premiere. The big thing about the ReliOn meters is that the test strips are so much cheaper. Most of the information you'll read on the site will be with using human meters. If you get a pet meter, you'll have to take the difference into account.
Next thing I wanted to mention is that the prescription food isn't necessary unless you just want it. There are many canned food, high protein/ low carb options for Tibby, and most are less expensive. The Purina DM pate is about 7% calories from carbs. The DM savory selects are higher in carb because of the gravy, so I don't recommend them.
There's a great food chart here, that lists tons of options. You're looking for calories from carbs under 10%, and calories from protein near 50%. I stay away from the ones that have too many calories from fat. You'll see that some of the options on the list have too much fat and not enough protein. Another thing to consider is phosphorus. It's best to choose flavors that have lower levels of phosphorous. Many members feed their sugar cats Fancy Feast and Friskies pates. I know it sounds a little crazy. I used to think Fancy Feast was like McDonalds for cats, but it's actually a well put together cat food.
I'm so happy Tibby was feeling more playful. It may simply take her a few days to get used to the insulin. When you do get a meter, test her about +2 (two hours after injection) to see what's going on with her BGL. As long as it's not dropping too low, she may just need time to adjust.
If you have more questions, don't hesitate to ask. There are so many awesome experienced members here to help.