My daughter was diagnosed in February 2007. I was feeling the same way as you are. We were all over the charts and I felt like I was hurting her more then I was helping her. It has almost been one year now and I promise you it does get better. We just went back yesterday and they are just now saying she is probably coming out of her "honeymoon period." We have changed her dosage chart and carb:insulin ratio probably 25 times. Also, it is AMAZING how quickly your child will be telling you what to do. My daughter, minus giving the needles, could probably survive doing this alone! She is amazing with it and they learn so quickly. She can tell me her number before we check very often. Hang in there!
Her body probably is still producing some insulin of her own, and when her pancreas activates and produces some insulin in addition to insulin she has already injected, a low can happen. This is called the 'honeymoon period' and it can last for months to years in some diabetic people. Eventually, things should stabilize some, and also in time, both you and your daughter will be better able to predict what her own body is going to do in reaction to certain activities and certain foods. In the meantime, the best you can do is to get her to test every 2-3 hours so she can catch those highs and lows before they get serious, and make sure she always has some juice boxes or cans (I personally love 6-oz cans of juice, for I think they are easier to open if I get hypo than juice boxes) with her at all times. I make sure that I never go anywhere without TWO of them, one for mild lows, and two in case a low is more severe.
The honeymoon period can cause complete instability, and things do settle down once the diabetic's immune system has completely disabled the pancreas. Meanwhile, she just will have to test often and adjust each time. And take careful note of how her body reacts to stresses such as school stress (do tests cause her to go high or low? how about physical activity?), daily activities,and sickness. It does get easier in time, and by the time she is an adult, it will all be second nature.
My advice is to not let this worry you now... just adjust often and don't stress over abnormal numbers. As long as you adjust when you see them, her glucose levels will normalize often throughout the day. This is our ideal goal, to achieve normal glucose levels as often as possible. So if you just have to adjust a lot, do it without feeling that she or you are not doing something right. This is all VERY normal for newly diagnosed type 1 people. I wish both of you the very best.