Is benching this much at my age good?????

I do MMA, seperate to that i go to the gym once or twice a week. I don't overdo it on the weights because i know it can damage your bones, and i make sure i use the correct technique. Last week was the 5th time i've started weighlifting and i bench pressed 70kg, the instructor spotted for me and said i did it correctly. However none of my friends beleived i bench pressed that much , is this quite good for a 15 year old?.