Diabetes is really complicated and I really feel for you.
Basically, with diabetes I think there is a honeymoon period where your body still makes insulin even though it isn't enough. Also, some t1s make a little insulin and some t1s don't make any at all. As a general rule, you should be doing about 1 unit of insulin per 10g carb that you eat and to add to make it even more complicated (this is how it works for me) it depends on how the carb affects you (i.e. whether it makes your blood sugar rise really quickly or is absorbed by your body a lot more slowly - please look up glycemic index on the net. This is really helpful, and I'm sure your dietician will advise you to try to stick to low to medium GI foods). I sometimes find that 1 unit is too much for 10g carb and with the breakfast I eat in the morning 4 units is too much for me, too. Lower your dosage - this disease is about you learning to alter your medication yourself. Go down to 3 units and see if your blood sugars are better. Then go down to 2 if you need to. You obviously need to discuss this with your care team, but it sounds like you are just taking too much insulin before breakfast and lunch, and then not enough with your evening meal. This is exactly what I was doing. Try counting exactly how much carbs you are eating for your evening meal and adjusting the insulin accordingly. Let us know how you go on, and please ask us for more advice is you need it!! You really shouldn't be eating to suit your meds, you should be altering your meds to suit you!! That's the whole point of you being on the basal bolus routine (which is basically taking 1 shot of long acting to last 24 hours and then 'topping up' with quick acting when you eat).
It sounds like you know what you are doing already, it's just a case of you gaining the confidence to adjust your insulin yourself. It sounds like a great idea for you to suggest to the nurse what changes you want to make and get the reassurance from her that it's correct. It can be quite scary to make changes yourself. I'm really glad your readings are a lot better!