I only see one object on your space-time diagram, that is a sideways (time going left-right) space-time diagram of a light clock with three cycles. (Usually space-time diagrams are drawn with the time axis vertical, not horizontal, but I can adapt to that. It's hard to tell from your 2d rendering of a 3d diagram, but it appears that x and y are constant at the center of the clock, while t progresses which is why I say it is a diagram of a stationary light clock, because x=y=constant is a stationary object).
I don't see any moving objects on your diagram at all. If you intended to make a space-time diagram with a moving object, you didn't do it correctly.
I would suggest doing a simpler task first. Draw a space-time diagram with only t and x, and draw the space-time diagram of a stationary object (x = constant), and a moving object (x = vt).
Next up, draw a space-time diagram of a stationary light clock, which should be similar to what you've drawn. It will be easiest if you make the diagram 2d - after you've got a correct 2d diagram (with x and t), you can add y to the picture, but it won't make any material difference.
The last step is to draw the space-time diagram of a moving light clock. I'm guessing that may have been your intention, but all I see is a space-time diagram of a stationary light clock and no hint of any moving objects at all.
[add] I'd also recommend drawing your diagrams at a scale where light always moves at a 45 degree angle from the x and t axis on the diagram.