make sure you are training hard enough to stimulate the muscle. your diet doesn`t look too bad so i`d say train harder.
unless you`re an ectomorph then you`d need to eat more
I`d say start tracking your food so you know exactly how many grams of proteins carbs and fats you`re eating. then based on your stats you can decide what to do.
don`t buy a weight gainer. and if you already have, throw it on the GARBAGE. as the above posters said, eat. weight gainers are crap full of sugar. (most of them)
throw the weight gainer on the garbage and EAT 6 meals a day. you should only have a weight gainer IF you are an ectomorph. but even if you are one I`d suggest you make your own meal. just add milk...
EAT. simply add foods that are high in calories like peanut butter, olive oil, oats, bananas etc. and make sure you eat plenty of complex carbs and proteins every 2 to 3 hours