Diet
I noticed you said you went
back to carb counting! Sadly there's really no getting away from carb counting - it's not something you can use temporarily and then let slip. The dietician should have given you exact guidelines - i.e. how many carbs per meal, etc. Insulin is then balanced against that, and over time you learn how much alteration is required due to eating more or less.
It may seem difficult to follow at first but believe me when I tell you things are much easier nowadays than ten, fifteen years ago. There have been massive advances in terms of companies displaying nutritional info on food packaging. The majority of products display carbohydrates per portion/whole item and most even show you "of which sugars" - (this is the part you want even less of - regular carbs give a gradual linear rise in blood sugar, sugary carbs give a quick sharp rise).
Also don't fall for any **** you hear about "portions" and "G.I" diet metrics. There's only one way to measure how much food you're consuming (vis a vis insulin doses) and that's by counting the carbs consumed.
Short version: Count Carbs all the time.
Insulin
As has once again been pointed out, Lantus is pretty pathetic. It was great in theory, especially as a single dose agent; but in practice Levemir blows it out the water - especially with a split dose regime.
Also, if she's not too high (low enough to avoid ketoacidosis) and has enough insulin in her system a quick bit of exercise will also lower her levels.
Other
It's not unknown for young girls to skip their insulin to get as thin as possible
Yeah and it's not unknown for them to be upset about the bruising on their injection sites.
Finally, don't panic. Blood sugar levels are like any other variable in a system - learn what effects that variable and make gradual changes. Results will follow.