Hang in there! It took me about a month before I really got the hang of it, and then after that it was easy. I would take the day off from the attempts - if you are stressed and he is stressed, it's going to make it a lot harder.
The secret is to find a routine that isn't stressful. For me, the picture changed when I went from desperately trying to force the test on my cat, to making it sort of a colaborative thing. I let him get used to the test kit, I played around with the lancet device without any lancet in it so he could get used to the noise and the feel of it, etc. I rubbed his ears off and on for a few seconds a few times during the day, so he would get used to having his ears handled.
Then I only tried to get an actual test once he was calm and didn't really care what I was doing, and I was relaxed too. For us, that approach made all the difference. I had gotten some tests before that, but they were accompanied by growling and running away (him & me, lol!), and then I never knew how I would get the next test. Once I shifted my approach, we got into a routine where I could pat the test spot and he'd come jump up, then I'd give him a little toy to focus on while I got the test, and then he got pets & snuggles & sweet talk.
Eating is important, so I would set aside the testing for the moment and focus on getting him to eat. Once he is back to eating regularly, then I would gradually try steps to get him used to the testing process, and just take it one step at a time and only move to the next step once he is comfortable with the first step. If he runs and hides as soon as you unzip the test kit, for example, you are already set up for failure. If it works out to have someone else come over too to help, that is a great idea to get you started. It's one of those things that once you get it working you'll be amazed at how easy it is, but it can take some experimentation and practice to find the routine that works best for the 2 of you.