Morning fasting levels are usually the last to come down. Do you test before you go to bed? If so, is there a big difference?
Do you have most of your protein for your evening meal? Protein does eventually break down into glucose (not all of it, only the spare bits left over after the rest is sent to do its normal job) and this takes several hours, even longer sometimes.
There is a thread called Pesky Dawn Phenomenon with a lot of information, and results of some experiments by members. It doesn't appear to be useful to have a snack at bedtime on the whole, but certainly give it a go. A fat snack might be best - no carbs - and not a lot. Maybe a mouthful of cheese? Someone else may be able to help more than I can. I never tried it. I found my levels came down on their own when I lost a certain percentage of weight (about 17% if I remember correctly) and now I am always more or less flat from getting in to bed to getting out again. A disturbed night won't help.
Sorry, I also can't help with the Amoxicillin. Not much use, am I? Lol.
Well done on your roast dinner reading! Brilliant.