Hello, Lovely! I'm sorry to hear you're so hard on yourself with your work! What I've read so far is beautiful. We're all just spilling our hearts and souls here on Medium, so you fit right in.
The more you open yourself and let out whoever is inside, the more you can also allow the rest of us in, so we can support and encourage you and cheer you on.
As for Grammarly ... it is often not correct! But if you do struggle with punctuation, spelling etc., it can help to some extent.
One thing that might help you with practicing writing what's in your heart is something called free writing and various other names.
Basically, you can pick a certain number of pages or a time period and you choose a topic - even just a randon word like pajamas or grass or mustard - anything! - and then you write write write whatever comes to mind
It has to be done with pen and paper, NOT computer or other device. And if you get stuck and don't know what to say, you have to keep writing, something like "I don't know what to say, I can't think of what to write" and you just keep going until you're back on the topic or wherever it took you.
The point of this exercise is to get out of your head and into your heart. There's something that happens after about 10-15 minutes and it's almost like meditating. You drop into a really deep, connected place and the words flow from deep inside yourself.
I've done some of my most powerful writing from this place. It can take practice to get there but it's worth doing - daily if possible - or at least a few times a week. I'd give it at least 30 minutes each time but remember, the most important point is DO NOT STOP WRITING. Write about how you can't think what to write if you get stuck, but do not stop.
Another thing DO NOT GO BACK AND CORRECT!! Do not scribble out, do not cross anything out - just allow the mistake and keep writing.
If you choose to do this, I would love to hear about it so please do let me know. It's a very powerful practice that can greatly improve your writing and also can help you be more accepting of what you produce.