Newly diagnosed

My daughter was diagnosed July 9th.  She is 10.  She had been having severe headaches since late February.  The pediatrician had done what she could and sent us to a neurologist.  He had her on 2 different 'preventative' medications for 'migraines' but she had a chronic daily headache that just wouldn't go away.  At the first of June she started drinking a little more than usual which eventually increased to drinking anything she could get her hands on and peeing constantly.  The Neurologist blew off the excessive thirst and peeing as nothing when it was still fairly mild.  After an MRI and a test for psudotoumor cerebri came back negative the neuro decided to put her on Prednisone.  She reacted severely to it but we didn't know why.  The neurologist said it was extremely rare for someone to not be able to take prednisone and send her a nausea med and said keep her on it (She only took 3 doses).  At diagnosis she had lost 13.5 pounds, down to 54 pounds, was in DKA with a blood sugar of almost 1000 upon arrival at the ER.  

We were taught how to give shots at the hospital.  She is currently taking 3U Lantus at bedtime and 3U of Novolog after meals with a sliding scale of 1 additional unit if her premeal BG is above 250 or 2 units if she is over 350.  Nothing given after snacks.

How long do kids usually stay on a fixed dose like this?  I know at some point we will adjust her dose based on her carbs but have no clue when we'll start doing that.

We have had no diet training at this point.  We go Monday to see a dietitian and a nurse educator at her diabetes clinic.  The only thing we were told was diet drinks and 'healthy diet like everyone should be eating anyway.'  That really doesn't help me any.  I am really struggling with meals and snacks.  She has been running in the 200's-300's pretty consistantly.  Her dose was just adjusted again Tuesday.  Her numbers so far today have been under 140.  She seems to always be hungry when she is high.  If I give her anything she just goes higher and feels worse.  Do you all have any recommendations?  Peanut butter is not an option.  I keep seeing that everywhere.  She does not like peanut butter and I am severely allergic to it.  She always wants an afternoon snack and a bedtime snack.  Those are the times of day her numbers are the highest.  She loves salad and is eating one at lunch and supper along with her meal.  It's hard to tell her she needs a salad for bedtime snack too :-(  She picked out some sugar free jello but now refuses to even try it.

Once you take a carb counting class, it'll be easier to give the right dosage. Sliding scales are so vague!

Cheese sticks, pickles, and carrots are a good option if she likes those. Most vegetables work in moderation. The bottom line is, if it is under 5 grams of carbs, it is "free," since having that little amount won't bring BG levels up.