It is good to hear you are losing your weight steadily, although you may find Slimming World diets aren't suitable for diabetics as they tend to be calorie controlled rather than carb controlled. You may need to adjust the recommended diets.
Until you are certain you have found the right diet that is suitable for you, this is the best way to test:
Immediately before you eat
2 hours after your first bite
Look at the rise from before to after
If it is more than 2mmol/l there are too many carbs in that meal
The idea is to keep the rise as flat as possible, ideally under 1.5mmol/l if you can
Keep a food diary including portion sizes
Record your levels alongside the food
Look for patterns over a week or two
This will show you which are your danger foods and in what quantities
You can try the same meal again with your reduced carbs and see what happens.
This is called eating to your meter.
Be guided by your meter and what it is showing you.
Many also test immediately after getting up before pottering about doing things. This is your fasting blood glucose (FBG) but be aware it is not a reliable marker of how well you are doing in general. Many also test before bed. How often you test is entirely up to you.
I hope this helps.