Depends on how much caloric surplus you are eating on a daily basis.

You ain't lifting heavy enough.

Also watch your diet. Are you eating enough protein daily? Are you having enough sleep?

You are bench pressing 26kg or are those barbell curls?

With such light weight, even 1000 bench presses won't do you anything. Your muscles won't grow when you aren't lifting heavy.

Since you're a newbie, you should try PROGRESSIVE OVERLOAD. Google it.

Try the Stronglifts 5x5 program. It's based on progressive overload and uses COMPOUND EXERCISES (drop the curls !)

Start from 20kg bench press. Do it 5 sets of 5 reps.
The next time you come to the gym, add 2.5kg. 3 gym days a week, you're already lifting 27.5kg and at the end of 1 month, you're lifting 50kg. It goes on and on...