As Daibell , it really helps if you are able to count carbs and  adjust your insulin  and it doesn't matter whether you adopt a lower or higher carb diet.
Carbs are  in pasta and potatoes but they are in a whole range of other foods and if you don't take the amount into account when you inject then your glucose will either go too high or too low.
For example  veggies aren't carb free. The amount of carbs in one homemade veg soup could be twice that  in another .  I just looked at one list on the fat secret site. There  were  some  veg soups that for me might  only  require 1-2 u of insulin  but one that would probably need almost 4u.  
 
  I got  the feeling that you are getting confused and were sticking with just those two foods  because you are uncertain and  fed up with the whole thing. It does take time and practice to learn how to do it.  
  I assume that your nurse gave you a starting point ie 1 unit for so many carbs you do need that for a starting point. You do need to know that.
. 
.
A lot of people  find the Carbs and Cals book or App useful. This is a pictorial  guide to how many carbs there are in various size portions.
http://www.carbsandcals.com/
It won't be as accurate as weighing and measuring your own portions but it's a good guide.
 
There are some  other resources  that can help. Unfortunately they are directed at T1 but I certainly know of  T2s who use the same methods successfully
This page has  links to a basic  carb list and a book about carb counting and adjusting insulin. ( the examples in the booklet are of fairly high carb meals but the methods of working things out are the same for lower carb meals)
There is also another link to an online course  that you can do at your own pace.
http://www.diabetes.org.uk/Guide-to-diabetes/Managing-your-diabetes/Carb-counting/