Levels all over the place?

My mornings levels are always normally around the same, on average 4.5. Occasionally 3.2 area if I wake up later.

However my hour after eating level yesterday was 7.9 all i had was a homemade burger on a wholemeal bun with onion, and a side salad. Today it was 4.3 I had onion and mushroom scrabbled eggs, with salmon, a side of broccoli and wholemeal pitta bread. I don’t understand the variation of my levels? Currently just diet controlled.