Suggestions to improve my routine?

I'm a 22 year old asian man, my height and weight are 1.72m and 51kg respectively.

I don't track my calories but I used to eat 2 meals a day to now eating 3 meals daily with a bowl of ice cream each night and a glass of milk before bed. I also started to eat 2 bananas a day in between meals.

I also started working out and this is what I currently do 5 days a week: 5×5 chin ups 15×4 push ups 12×3 bicep (5kg) curls 12×3 dumbell (5kg) squats

I started 3 weeks ago and only gained 1kg so far. Is this a good enough change in my lifestyle to one day reach a normal BMI? What changes should I do to improve?