hi Lisa! You sound pretty discouraged - I can't imagine doing this for a year without the support I found here on FDMB.
Before you make significant diet changes, let's help you get hometesting. You can totally do this! It's not hard at all once you get the hang of it. An important thing for you to know is that a cat's ears will grow more capillaries when the poking (testing) happens. It stimulates the growth of new capillaries. People starting out often get discouraged because they don't get blood at first, and they think they're doing something wrong, but in about 2 weeks of poking you'll get blood to test pretty much every time. In the meantime the poking is helping to grow capillaries, so it's not worthless. Don't give up on it!! I always gave punkin a bite of cooked chicken breast after his tests and it wasn't long until he accepted it. I confess that at first I had to burrito-wrap him in a big towel, pinning his front legs to his chest like a little shrimp, to test him. But he gave up, I got better, and that phase passed. His bite of chicken made it all worthwhile for him.
Here are 2 posts that people have contributed to with their best testing & shooting tips. As Chris said, a warm ear bleeds better and a treat afterwards soothes hurt feelings, whether or not you got blood.
http://www.felinediabetes.com/FDMB/threads/hometesting-links-and-tips.287/
http://www.felinediabetes.com/FDMB/threads/testing-and-shooting-tips.85113/
Once you're testing at home and have a spreadsheet going, then I think Chris' ideas about switching to a low carb food is great. The reason I'm suggesting getting testing first is because that 4u is a significant dose - although I had a kitty with a high dose condition who needed more insulin, as some cats do. The thing is there is a relationship between the carbs the kitty eats and the amount of insulin they need, and if she's ok with 4u right now, we wouldn't want to signicantly reduce her carbs without reducing the insulin if she needs that. Tests will tell us what's going on in her body with her blood sugar, so the dose can be adjusted accordingly. That's why it's important to start testing first before changing her food.
One more important point I want to mention - not all high numbers mean that a cat needs more insulin. That's why it's possible that even though you're seeing high numbers at the vet's, it may not mean she needed dose increases. It is possible she needs 4u with the dry food. we don't know yet. Blood sugar doesn't stay constant. One test of 300 means pretty much nothing - a cat can be at 300 and 4 hours later test at 30. We've seen it many times. That's why we're so pro-home testing here. It's the only way to know what the insulin is doing in the cat's body.
We all use a spreadsheet to track blood sugar. It's an essential tool for seeing what's going on.
Here are directions on setting one up - if you have trouble, just holler because people will help you if you need it.
I don't want to overwhelm you with too much info, but just know that people will help you here. You're not alone anymore. Hopefully we can help you help your sweet girl (what's her name?) feel better.
Ask as many questions as you have. The more the better.
julie