How to unlock true power?

So. I’m 100 kg and abou 185cm. Now I’m not fat I’m big boned, I’m 35 years old. I started muay thai 1 year ago. In my gym there are mostly young guys 21 ish.

I’m a big guy for sure with over 30kg on them. How can I ensure my punches and kicks are harder and more powerful than theirs? I feel like such a wimp sometimes when we are doing pads and they whack so hard when I don’t as hard.

Punches are fine. Kicks I can do well but I’m limited, my hip flexors just don’t want to stretch and get stronger after a year.

What tips can you give me on this?