What are normal levels?

How low is too low for an after meal reading? For instance my fasting number before breakfast was 69 (yay) after breakfast (egg, a slice of wheat bread toast, and a slice of bacon with two or three slices of apple) it was 122 (again yay) then for lunch I had a protein drink and about a half an apple and my number was 78. Seeing as that’s only ten points off of my fasting number I feel like it was way to low but I have no context for what is to low, all I was told was to be under 130 an hour after I finish eating. Does anyone know?