I can't even whistle, Sarah, so I have no words of advice! However, I would think that singing--like every other craft--is something that is continuously improved over time with education and practice. It's interesting to compare/contrast early recordings of an artist, particularly a prolific one, to later ones and hear how their voices have developed during the course of their career. Buddy Guy is one example; in his early recording of "Let Me Love You, Baby" (laid down in the 60s, released in the 70s on his I Was Walking Through the Woods LP, I think), his vocals are tentative and almost a little shaky. In his version of that same song from Damn Right, I've Got the Blues ('91, I think), he sings it skillfully and forcefully. In addition to that, the guitar work in the latter version sounds like technology caught up with him by then. I'm sure you've also noticed how Joe's voice has grown, so-to-speak, from ANDY to You & Me, too.
BB King has maintained over the years that he can't sing & play at the same time, but I don't think any of his fans mind, and it certainly didn't put a damper on his development as an artist. I'm sure that you, too, will overcome any bumps in the road as your playing and singing merge.
"The Blues is like a tonic for all that ails you." BB King
Rock ON & Keep the Faith!