number 1 is to keep offering the other foods - so if she is eating fish fingers (which she loves) then try to get her to try carrots or broccoli florets with it instead of peas and corn (which my 2 yo loves as well). even if she does not eat it offer the foods over and over. My daughter would not eat rice or potatoes until recently. i had actually stopped offering them a long time ago and then tried again - and she ate it! you really never know the day they will just go ahead and try it...
second - have you tried sharing meals with her (even if yours is just a tiny portion to be involved) - this is how my 2yo ate cheese finally. i was the only mom whose kid woudl not eat string cheese, cheddar, etc and then when we had dinner together Dh offered her some sliced pepper cheese from our salad and to my shock she ate it anbd said mmm! and proceeded to pick it all out of our salad. now she still won't eat the bland cheeses but loves brie and blue cheese :lol:
third - since she loves breakfast- have you tried offering breakfast type foods at other meals - i actually never serve eggs for bkfst because i know alex wil eat cereal or porridge etc so saved eggs for lunches and dinners which were trickier. i will do eggs, toast with marmite, and some veg on the side. or pancakes with fruit and yogurt, etc
is there no fruit she will eat? i have a fruit lover (who goes through phases so i never know which she will eat that day, but i ask her to pick). if you have always done basic apple or banana to no avail, maybe you can make a game of it and prepare a fruit salad together and try the different fruits - buy 1 of each thing (try different berries, peaches, plum, pears, etc) and maybe she will be relaxed as it is just snack time and she will show you she likes some of it...
just some ideas - good luck!