Hi Sonia, and welcome. It's great that you're home testing! That's such an important step in caring for our kitties around here!
What type of dry are you feeding? I'm asking because the percent of carbs in a cat's food has a huge impact on their blood glucose (BG). In fact, it's probably the single most important factor in helping our cats heal.
It sounds like the 0.5u might not be enough insulin, but don't change the dose just yet. First, can you set up a spreadsheet? We have a handy dandy one already made that does all of the color coding for you. If you click on the blue text in my signature, you can see what one looks like, and then if you click on the link below, you will have all the directions for getting your own all set up. If you have any trouble with it, just ask and we can have someone help you.
http://www.felinediabetes.com/FDMB/threads/fdmb-spreadsheet-instructions.130337/
Finally, can you go up to the top and edit your title? We only use the 911 for emergencies like when a cat is having a hypo episode, or ketones, or something like that. When we see those red 911's, we all panic a little bit.