Thanks for the input.
I had meat (plus veggies) for lunch and I injected just one unit. It was good that I did that since I could see a moderate upward movement of my BG (it peaked at 6) even with the bolus.
For dinner I had one smal avocado and lots of other low-carb veggies with olive oil. Again, I injected one unit. But this time I went a little bit low (around 4), so I ate a slice of crispbread (6g carbs) and pistachio nuts (about 10g carbs) .
My conclusion would be that proteins made the difference. (I had meat for lunch but almost no proteins for dinner). For foods with carbs I would just count the carbs. When there are no carbs, I suppose one should count the protein ??