Having your own "voice" shine through your writing is important in order to make your reader remember you. If you read through your favourite books and favourite blogs you will find that every author has their own quirks. Some words or some phrases they prefer to use, some way to structure their sentences and paragraphs, the length of their chapters or articles and how they introduce new characters, places and events.
It's important to be true to yourself and give your readers something to look forward to. If you change your writing style completely to fit your target audience you will likely not catch every time you are using your natural writing style, which your readers will catch.
Other than that you shouldn't get too worked up about your voice. If it's readable it's fine. The differences between different forms of the english language are not that big if you don't write the way dialects sound (Irish for example: "Yer know what a mean, lad?"). Different idioms might be difficult for people with other mother tongues, but normally it should be pretty self-evident what you mean judging by the context.
English is spoken all over the world. Many people can speak at least a little bit of english, even if it's not perfect. But that also means that they will likely have as much difficulty reading American English as they will have reading British English, Australian English or any other form of English.
Just go with what feels natural and focus on the content of your writing. Try to fascinate your readers with your stories, get them hooked and listen to their feedback. If you get feedback that indicates most people don't get half of your posts, articles, stories or whatever you are writing you should try to accomodate them a bit. Find a way to explain idioms and proverbs in a way that feels natural and doesn't stop the flow of your writing too much.
Don't think about solutions to problems that don't exist yet.
Get your writing out there, try to find an audience and see how they respond to your writing. English is a good way to have a potentially large audience - no matter if it's American, British or some other specific form of English. Many people start with British English in school, but also learn American English later and get to know different dialects through movies and the internet. They will likely mix them up quite a bit in casual interaction and therefore won't really mind one way or the other. In the end it's all the same to most people.
I myself am often mixing up American and British English as I am from Germany and I only realize this problem when someone tries to fix my English one way or the other. That's also the only situation in which I actually realize that someone is using one style or another. Whether someone writes "colour" or "color" is irrelevant most of the time, as is whether a proverb I don't know is British or American. Try to be consistent, but don't get too hung up on it.