Props to Leonardo Muller, your Darlington transitor KIP125 solved my problem and now i can even trigger on the base with a resistor of 1k ohm instead of 330ohm. I guess the hfe=1000 really helps a lot and the problem is definitaly lies within the current requirement for buzzer circuits.

And thanks to Erik Malund as well for helping out and your suggestion to measure the current does make sense even though i couldnt measure it on my multimeter. I didnt know what is wrong, but whenever i try to connect the ammeter in series with the buzzer circuit, it will distort the sound being produced and the current reading became stable. Maybe there is something wrong with my digital multimeter.

anyway, the problem is solved now, extra thanks again to leonardo and everyone that has helped out along the way!

If there is anymore problem in the future regarding my project problem, i would be expecting helps from you guys again :)