Thank you for the fast reply!
I have type 1, currently on injections, and was only diagnosed at the end of September, so everything is still very new and overwhelming.
If you are new, you may also be experiencing the honeymoon period.
This is where your pancreas may still be producing some insulin. Unfortunately, it is not consistently producing insulin. Some days it may be on full insulin producing power (and you may experience hypos) and some days it may wear itself out and produce no insulin (so your levels go high).
The other thing I neglected to mention above is that some food can be absorbed slower than others, especially if they contain a lot of fat. For example, a cheese sandwich may result in a high blood sugar level in the afternoon because the bolus insulin is used up before the glucose peak.
To be honest, my advice (but I am not a doctor) would be not to stress about levels around 11, if these are spikes (up and back down again) rather than plateaus (up and stay there).