Sorry to bring bad news, but your gp is kinda slack!
Diabetes is pretty complex and you need to be under the care of someone who has in depth knowledge. Most gps aren't equipped to deal with it. Get him to refer you to the diabetes specialist at your local hospital. It's your right, and it's his duty to sort it.
There's a lot to learn unfortunately. Your blood sugar shouldn't go above around 8 generally, and anything under 4 is a hypo. The best way to control it is to count the carbs in every meal, test your blood sugar before you eat (and always test if you feel ill or weird), then adjust your dose of fast acting insulin to cover each meal. DAFNE (dose adjustment for normal eating) is a 5 day course which will teach you how to do that properly, and more. It's totally invaluable. I had ****** control for 22 years, thanks to never getting adequate education, until I did the dafne course in January. Now I have a decent (not brilliant, but decent) HbA1c for the first time ever, and feel like I'm in control of the diabetes, rather than the other way around. So I would strongly recommend it.
As for carbs, you need to count the total carbohydrate in foods, not just the sugar. Sugary food within moderation is ok as long as you inject enough to cover what you eat.
Testing once a day is absolutely not going to work. You need to test before you eat, some people test 2 hours after to find out which foods cause a spike, you also need to do it before exercise, before bed, if you feel unwell, and before driving.
I hope your gp can get you referred quickly, as he has some fairly huge gaps in his knowledge. Good luck!