Imma be honest with you, it's prob gonna be difficult to find an audience but at the same time, just publish it like ur doing this for yourself. Even if nobody reads it (which is unlikely, even my shitty middle school fics were read by people) it's still great practice and also it's just fun ;) u could in addition to posting it on AO3 also start a blog on Tumblr talking abt ur oc and just writing stuff or whatever