first thing your boxes are too small you should have drawn them bigger so you can extend the lines more to see where you are going wrong

my advice to you is when you start drawing the box start with the Y letter and make sure all the dregrees are >= 90 then try to make the vanshing points in your head and start drawing the faces so every 2 faces go to the same VP

also i noticed that you cross hatching the wrong face alot you are doing it to your self so you understand the face that you are looking at better which might mean that you are not imagining the box in 3d space enough try to imagin it in your head more and start slow doing the steps i really recommend you practice it more