Write the song even if you can’t sing. Someone else might. Or you’ll learn.

Writing and performing are separate jobs that often get confused for one. A song exists as words and structure before anybody sings it, and plenty of songs people love were written by someone who would never perform them. Deciding you cannot write because your voice is weak throws away a skill you may well have. The two can be learned in either order.

Finish a song without worrying how it sounds in your mouth, and record it roughly just to hold the shape. Offer it to somebody whose voice suits it. Keep writing while you work on the singing, if you want the singing at all.