Hi wurlitzer, and welcome to the forums

I started writing music when I was around G2-3 - just simple tunes to verses that I'd written. I asked around locally about learning composition - only one teacher was willing to take me on at that level and it turned out that what we would have been doing was in effect learning theory up to at least G5 first. And you learn a lot more about composing if you do G6-8.
If you want to find a teacher locally to ask about composition lessons, have a look at
musicteachers.co.ukYou could consider putting your compositions into a programme like Sibelius which I
think lets you do it free online but you can't print it off. There are other programmes as well which may let you do this but I'm not sure. If your composition skills are more advanced than your piano skills at this stage, you could then play around with what it sounds it more easily.
But in the first instance, I would recommend getting to G5 theory as quickly as possible to at least give you some grounding. And carry on doing your compositions informally in the meantime - it's fun, innit!
Hope you enjoy the forums

PS. I'm not a teacher by the way, wurlitzer, I'm just an adult student with an interest in theory and composition.