I have found that pretty much every fruit i have ever eaten has raised my BS, proteins raise my sugars but ~3 to 4 hours after eating them.
To do a basal check you have to ingest no food or drink that may impact the results of the test. To produce the best results you should be fasting.
With many people (especially those not on CGM) they say proteins don't impact blood sugars, but what is really happening is they aren't obtaining enough data points to notice. Even with a CGM detecting the effects of proteins is tricky as it typically raises the BS level such a small amount over such a long period (~1 mmol/l over 3 or so hours) that people claim it doesn't effect them, but it does. In everyday life this change may be negligible to many, but not all. And during a basal test this can pretty much destroy the accuracy of your results because the protein holds the sugars steady making it seem like everything is spot on, when in reality it should have dropped those 1-2mmol/l.
Its always best to FAST for basal tests. Fasting is no food at all, for at least 6-8 hours during the period you want to test, sometimes this involves skipping meals.
As adults, this lack of food won't kill us, and knowing we have generated quality results is more then worth it in my books!
Also- Doctors are not always correct. No offence, but anyone can be a doctor, and just because a doctor used to be on their A game in med school does not mean that they are up to date with things today. Nice people can be poor doctors, and vice versa, so never judge a persons professional skill with their personal skills haha