Why is my homemade 3D Model in Minecraft not showing up properly on inventory?

So I'm doing my own furniture mod for Minecraft. This furniture I have modeled on Blockbench and then saved it as a JSON file and on MCCreator I have imported the JSON file and then set up, and when I wanted to test after setting up for Mod I find that my furniture on inventory is not displayed correctly becomes. Because the ad seems too big. Look at the pictures:

And this is what it looks like when I hold my hand:

Yes, and that looks really bad. I do not know how to fix it so that all my self-styled blocks are displayed properly small?

Hi, you can save the chair from the desired perspective as a square image. Then it should work. 3D files are always displayed in Mincraft as 2D.