Simply increase your dairy products, eggs and peanut butter (not sure if it's expensive where you are, but it's cheap here). Also, buy a cheap protein powder.
So have a moderate amount of carbs, but make up the rest from fats/protein.
I made some of my best gains from cream and whey shakes (yes, you heard that right - cream! lol).
Suppose you could say most of my training has been vegetarian (but plenty eggs/dairy), not because of moral issues, but simply circumstances; meat's expensive when you're on a really tight budget
You still are taking in mostly carbs (probably somewhere over 60%). I'll give example meals based on what you've been eating (roughly 600-800 cals/meal):
-100g oats & honey
-300ml whole milk + 50g whey (get a PLAIN protein powder, bin that "mass gainer" crap...just full of sugar and making you fatter!)
-1/4 cottage cheese
-1 cup milk
-1 chicken breast
-1 cup of broc
-milkshake (cup of milk with 1 banana)
You get the gist.
^ Those meal's macronutrient ratios are about 40%/30%/30% (Carbs/Protien/Fats)