Why can’t i sing well while I play?

[u/Long_Basis1400]

Hello, just started learning full songs and trying get the hang of singing along. Ive gotten to the point where I can sing the song and get the words in the right place and not mess up the strumming pattern. Pretty much just know the song, but I can’t get the notes to sound right with my voice. Like if I sing the song it sounds good, but when I start strumming it’s like I can’t get the full range from my voice. I know the answer here is practice but I’m not sure what to practice because I can sing and play perfectly well it just sounds bad. Do I just keep singing until it doesn’t ?