How to List Management Experience in Job Applications

I just got my third rejection where I was told that I was a strong candidate but the deciding factor was another candidate having more management experience. I'm currently employed as a library assistant and am building management experience by serving as volunteer coordinator and as a committee chair, but I've only been doing that for two years and one year respectively, which I realize isn't much.

I was talking to a friend about the rejection and the management experience situation, and they suggested that when applications ask how many years of management experience I have, I should count each thing I do separately or do it as a range (ie enter 2-3 years because I've got two years as volunteer coordinator and one year as committee head for a total of 3). I feel like that's dishonest because I've only been doing management-related things since two years ago. Either way, I'm elaborating on everything I do on my resume and in my cover letter.

Which of us is right? Am I underselling myself, or is my friend suggesting that I inflate my numbers? I'm feeling kinda down about this latest rejection since it sounded like I did everything right but someone else had a higher number on their application, and I could use some advice.