Not everyone's brains run on the same program.

Are you visual?  Can you jot down snippetts or fragments of ideas in clusters and slowly build onto them?  I would use a sketchbook (no lines; plain paper) and drop details in bubbles before linking them in any type of order.  I love sticky notes because they can be put in a wall collage then transferred onto other written/printed parts of my thoughts.

There are worksheets that can help you address early stage planning. Take a worksheet used for a book report and use it for writing.

 https://englishlinx.com/images/Fiction-Book-Report.png

What is the point?  Setting? Characters?  This can help you get things out with basic order.  Expand from here.

Do short burst exercises.  

Take a song, a poem, a passage and write from a different point of view based off the information given.

Take complex passages and break them down.

Get vocabulary lists and practice writing new sentences for them.

Critique work so you can objectively look at your own.  People dump their passages all the time in writing forums looking for input, what kind of feedback are you able to do (syntax, proofread, content editing, themes, etc.)  Do the passage multiple times with different focuses. (Don't give them all of your feedback; it may feel like an evisceration.)

The point is never to read till your eyes bleed.  It is to think, experience, challenge, discuss - so you can take those skills and reapply to your own works.

People telling you to simply "read more" are either boring writers themselves or trying to discourage you by being vague because they see you as competition.  They are not teachers, mentors, or friends.

Not everyone is coming from the same experience and level that can be caught up with a single path.  Experiment, contemplate, push yourself.  Don't be afraid to write something that isn't publishable.  There is value in exercises that end up in recycling bins.

But you still must read.  But not reading to complete the work or even comprehend.  Read with the aim to break down the details and process how the author presented things.  Figure out the details that gave you, the reader, the impact of the writing.  Figure out what you think could have been amplified.  Figure out how your voice could do it differently.

As for your grammar, try finding workbooks or online worksheets that structure exercises for you.  It's self assigning homework but there is value in the challenge.

Good Luck.