Is it normal to have trouble saying i love you?

Is it normal to have a hard time saying I love you? I can't seem to tell people that I love them even if I do very much. I can't tell my mom that even though I do and feel bad when she's gone. My mom isn't really affectionate though. I don't know why I can't say it or feel embarrassed/awkward when it comes to saying "i love you" or showing any affection towards others. I show my affection more by doing things for others and putting their needs and everything before me and my needs. Why do you think this is?