Hi Rosie, it's virtually impossible to compare different people's insulin requirements, I'm afraid. There are some very general rules, like number of units per kilo of body weight and also having your total daily dose split 50:50 between bolus and basal (fast and slow insulin), but these are really only useful for setting initial doses,which then will need adjusting to suit the person more closely. Some people need a lot and some people hardly need any.
Are you getting a lot of hypos or a lot of highs, or both? The Ragnar Hanas book gives some guidance on how to adjust insulin (Chapter 15), so if you can get hold of a copy it might be useful:
Type 1 Diabetes in Children, Adolescents and Young Adults