I second this and highly recommend it. On a major plus side, you don’t have to show your face or reveal your identity, so you can be completely anonymous. I’m mentioning that, since they have a voice record function where you can record yourself speaking and upload that for people to correct as well. You mentioned having fears of speaking, very understandable, but unfortunately the only way to get better at speaking and become more confident, apart from therapy/psychology related solutions, is to just speak more.
Here’s my tips:
-Speak to yourself as often as possible. Start with anything, say anything, it doesn’t matter. Do you see a window in your house? Great! Say: これはまどです。In the shower? Perfect! Practice there too, I do that a lot as well. Have fake conversations with people. Even if it’s only はじめまして levels. The more you speak, the better you will become.
-Shadow tutorials. Japanese Ammo with Misa and Dogen on YouTube would likely be places to start. (There are so many more, but I mentioned shadowing tutorials specifically since it can simultaneously get you used to speaking more advanced while understanding what you’re saying. You can 100% shadow anything you want though, and it’s highly recommended in general anyway.) This goes along with things like Pimsleur. Shadowing is where you repeat what is said by a native speaker. I recommend doing it several times, and not just once, but once is obviously better than nothing if you’re short on time.
-Speak to your reflection and/or record yourself speaking. These will be more difficult to someone who has trouble already with their voice, but it’s still good practice. Remember, only YOU will be there in front of the mirror and only YOU will have access to your recordings. If you can, try listening back to your recordings. It sucks, but it’s helpful to figure out where you are at in terms of your level. How accurate are you pronouncing things? What words did you mess up? Where could you improve?
-Write! (Or think! xD) Any production makes a difference. I’ve found that the more my brain has to work for me to type out sentences or replies on HelloTalk, the better I am later on when speaking to my Italki tutors. I still 1000% recommend speaking, but if you find yourself especially tired or otherwise unable to sometimes, still take advantage of writing/typing. (Places like HelloTalk are so great because you can get corrections!) The process will be slow at the start, but just like any other skill, the more you do it, the faster and better you’ll be at it. Everyone is there to learn, so don’t worry about making mistakes. Making mistakes is super important as it’s how we learn! <3
-Plan scripts. Start simple with a self introduction. I got this idea from ‘Fluent in 3 Months’ email newsletter that I signed up for years ago but never read any of them until like last month LOL. But here’s what he says:
When I start learning a language, I use what I call “Tarzan Speak”. Tarzan’s the guy who was raised in a jungle, so he wasn’t too hot on grammar.
Imagine for a moment that I’ve just started learning English. We meet, and I say:
“I Benny. I blogger.”
It’s terrible grammar. Truly terrible. But you’d understand me, right? And I’d be practicing my English.
That’s Tarzan Speak.
He recommends starting with an introduction of yourself, a bit about your family, your hobbies/job, and then adding sentences starting with, “I am…”, “I like…”, and “I have…”. The idea is to memorize this script so you’re able to use it if you need to.
-Your idea of a journal is a good one, and one I’d recommend too! I used to do it more often, been slacking recently, haha, but I would treat mine like a sort of diary. I’d make a few sentences about my day and write them down. “I went to the grocery store today. It wasn’t surprised, but disappointed with all the toilet paper still being sold out. People are stupid.” Or just keep it to one sentence at the start. “I went shopping today.” It doesn’t have to be complex, again, the more you do, even if it’s simple, will start to get you going places 
-Once you gain some confidence, it might be a good idea to look into a partner. Italki doesn’t just have tutors, it also has a set up for language exchange that’s free. (You can do this on HelloTalk too, but I don’t think they have video chat?) You can talk to someone who wants to learn English (or whatever language) and is around your Japanese level. Split the time in half, half your language, half their language.
-While this tip won’t seem like it’ll directly help with speaking Japanese, I assure you it will–speak English/your native language. Do it in the mirror, watch yourself speak, record yourself and listen back to it. You mentioned having extreme embarrassment about your voice, which is why you can’t speak. Getting used to yourself talk, as hard as it might be, will eventually help you relax more when speaking. (I did this the hard way by making a YouTube channel years ago and having to edit the audio. Was really tough and awkward at first! And when I started including my face too, oooh, it was so bad! But now it’s much much easier, and I found that even in IRL conversations, I’m much better too! It builds confidence 
)
Obviously being in Japan (and actively trying; people can live in Japan and never learn!) or having direct guidance will be the best bet, but there are still ways to go about studying and learning on your own. 
I wish you the best of luck and hope my tips helped! ^^
Instead, I would like to focus on my ability to output Japanese in text form, which is sorely lacking at the moment…
)
This “private” production can help us get used to quickly translating ideas into something!
Or just random posts on HelloTalk will catch the attention of native speakers too – you can set a “please correct me” tag and people will post corrections.
It’s a 30-minute speaking and listening lesson, in which you can do it alone, no one will judge you. 
Basically, the speaker will asks you questions (pre-recorded) in Japanese and you have to answer back in Japanese.
We are all 上手 or nothing.