Your latest model has a bunch of internal faces which will prevent it from being printable until you clean it up. It shows evidence that you laid out all of the features in 2D before making it 3D.
I think you would find things a whole lot easier if you start thinking in 3D as soon as possible. Wait to outline the features until you get to them. Imagine how the printer would print this thing if you have it in the same orientation.
Also keep your models closer to the origin. That helps prevent some weird graphics issues.
Here’s a quick example of modeling your component.
Draw the outline of the bottom face.
Extrude to thickness of the lower part. Then outline the relief on the inside.
Extrude to the height of the bottom of the groove. Outline the sides of the groove.
Pull the faces up to leave the groove and create a component (or group). Immediately, without any clean up required, the thing is solid and ready for the .stl export and 3D printing.