Hi, new to the forums.

I`ve been writing songs for a couple of years now but I`m convinced I`ve been singing in the wrong key.

What I thought was wrong with my voice turned out to be more connected to my guitar playing (i.e. the chords/key I was in) I write in my head but by the time I get to guitar I find I`m constantly singing slightly out of my range to accomadate the sound coming from the guitar. I`m hopeless with music theory, but I was wondering if anyone else has encountered this and if so, what are the possible fixes to change into the right key that fits your voice (capos? different chords?)

Howdy, I understand your question.
I would probably need to know how good you are on the guitar, open chords only, mostly? Theory is fun. If you have a song in your head, try to match the notes you are singing, and are comfortable with, to single notes on the guitar. In other words try to play some of the melody of the song on the guitar. Pay attention to what notes you are playing, hopefully you know the notes on the fretboard, and then pick the key you would be singing in on the guitar. Find the "tonal center". For instance, if you are singing C, D, E, F, G, A, B notes with your voice, you should try playing C, F, and G chords which would put you in the key of C. Or G, C, and D chords which would put you in the key of G. These three chords in their respective key are known as the I, IV, and V chords which is what 99% of songs are written around. Pick a key and that key would be the I and count up the scale, alphabetically, to find the IV and the V. If you find your singing notes fall on some goofball chord like Eb, Ab, or Bb,
move your melody to an easier key, up a half step or down a half step, for the guitar so you can utilize the open chords. Tada. The guitar is built in E and doesn`t like flat keys, especially Eb. The keys you will feel the best in on the guitar are: E, A, D, G, and C. All other keys will necessitate bar chords and uncomfortable positions. The other chords you may look for in accommodating your melody would be the vi chord, which is the realative minor of what ever key you are in. Example:
Key of C. Count up six notes of the C major scale with C being one.
cdefgA. Amin is the relative minor for C. And do that for all the keys above. The exception in this case is the vi chord in E. That would be C#min because the key of E has four sharps with C being one of them. I hope this helps. You have my email and I would be glad to help you with stuff like this if you need it. Theory is just simple math. Roy