Somehow i am not as concerned right now about you overdoing it as i am about the person who told you to be careful. It sounds to me that the person is either burnt out or is a little bit selfish.
As a bochur it is quite admirable that you go out of your way to do cheesed. When you are older and have more responsibility it will be more difficult for you to do some of the things that you find so easy to do at the moment and you will not be so able or willing to do them later on in life. So going out of your way to do a favor, or a cheesed that makes you a little late now and then, and doesn’t bother you right now should not be a concern for someone else.
Everyone has their own ways of doing Chessed and they can change over time depending on one’s circumstances and responsibilities. Right now you don’t have many obligations other than to yourself. Later on you will have obligations to your wife, children, maybe a boss, etc. and your time, and money will no longer be just your own, so the way you do cheesed will change. Of course the things you do today strengthens your heart in the right direction so you will ALWAYS be willing to do cheesed in whatever ways you will be able to. So please do NOT worry about it and just be yourself.