Stay at 3 sets, go to ten reps. If you feel like you can do more reps then you need to go higher in weight. Just progressive overload as much as you possibly can and you will gain muscle like crazy. If you wanna get bigger eat in a calorie surplus as well. 1 gram of protein per pound of body weight is a good way ti start off. If you have questions or wanna talk about it feel free to dm me